[ Upstream commit bffacdb80b ]
cilium bpf_wiregard.bpf.c when compiled with -O1 fails to load
with the following verifier log:
192: (79) r2 = *(u64 *)(r10 -304) ; R2=pkt(r=40) R10=fp0 fp-304=pkt(r=40)
...
227: (85) call bpf_skb_store_bytes#9 ; R0=scalar()
228: (bc) w2 = w0 ; R0=scalar() R2=scalar(smin=0,smax=umax=0xffffffff,var_off=(0x0; 0xffffffff))
229: (c4) w2 s>>= 31 ; R2=scalar(smin=0,smax=umax=0xffffffff,smin32=-1,smax32=0,var_off=(0x0; 0xffffffff))
230: (54) w2 &= -134 ; R2=scalar(smin=0,smax=umax=umax32=0xffffff7a,smax32=0x7fffff7a,var_off=(0x0; 0xffffff7a))
...
232: (66) if w2 s> 0xffffffff goto pc+125 ; R2=scalar(smin=umin=umin32=0x80000000,smax=umax=umax32=0xffffff7a,smax32=-134,var_off=(0x80000000; 0x7fffff7a))
...
238: (79) r4 = *(u64 *)(r10 -304) ; R4=scalar() R10=fp0 fp-304=scalar()
239: (56) if w2 != 0xffffff78 goto pc+210 ; R2=0xffffff78 // -136
...
258: (71) r1 = *(u8 *)(r4 +0)
R4 invalid mem access 'scalar'
The error might confuse most bpf authors, since fp-304 slot had 'pkt'
pointer at insn 192 and became 'scalar' at 238. That happened because
bpf_skb_store_bytes() clears all packet pointers including those in
the stack. On the first glance it might look like a bug in the source
code, since ctx->data pointer should have been reloaded after the call
to bpf_skb_store_bytes().
The relevant part of cilium source code looks like this:
// bpf/lib/nodeport.h
int dsr_set_ipip6()
{
if (ctx_adjust_hroom(...))
return DROP_INVALID; // -134
if (ctx_store_bytes(...))
return DROP_WRITE_ERROR; // -141
return 0;
}
bool dsr_fail_needs_reply(int code)
{
if (code == DROP_FRAG_NEEDED) // -136
return true;
return false;
}
tail_nodeport_ipv6_dsr()
{
ret = dsr_set_ipip6(...);
if (!IS_ERR(ret)) {
...
} else {
if (dsr_fail_needs_reply(ret))
return dsr_reply_icmp6(...);
}
}
The code doesn't have arithmetic shift by 31 and it reloads ctx->data
every time it needs to access it. So it's not a bug in the source code.
The reason is DAGCombiner::foldSelectCCToShiftAnd() LLVM transformation:
// If this is a select where the false operand is zero and the compare is a
// check of the sign bit, see if we can perform the "gzip trick":
// select_cc setlt X, 0, A, 0 -> and (sra X, size(X)-1), A
// select_cc setgt X, 0, A, 0 -> and (not (sra X, size(X)-1)), A
The conditional branch in dsr_set_ipip6() and its return values
are optimized into BPF_ARSH plus BPF_AND:
227: (85) call bpf_skb_store_bytes#9
228: (bc) w2 = w0
229: (c4) w2 s>>= 31 ; R2=scalar(smin=0,smax=umax=0xffffffff,smin32=-1,smax32=0,var_off=(0x0; 0xffffffff))
230: (54) w2 &= -134 ; R2=scalar(smin=0,smax=umax=umax32=0xffffff7a,smax32=0x7fffff7a,var_off=(0x0; 0xffffff7a))
after insn 230 the register w2 can only be 0 or -134,
but the verifier approximates it, since there is no way to
represent two scalars in bpf_reg_state.
After fallthough at insn 232 the w2 can only be -134,
hence the branch at insn
239: (56) if w2 != -136 goto pc+210
should be always taken, and trapping insn 258 should never execute.
LLVM generated correct code, but the verifier follows impossible
path and rejects valid program. To fix this issue recognize this
special LLVM optimization and fork the verifier state.
So after insn 229: (c4) w2 s>>= 31
the verifier has two states to explore:
one with w2 = 0 and another with w2 = 0xffffffff
which makes the verifier accept bpf_wiregard.c
A similar pattern exists were OR operation is used in place of the AND
operation, the verifier detects that pattern as well by forking the
state before the OR operation with a scalar in range [-1,0].
Note there are 20+ such patterns in bpf_wiregard.o compiled
with -O1 and -O2, but they're rarely seen in other production
bpf programs, so push_stack() approach is not a concern.
Reported-by: Hao Sun <sunhao.th@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Co-developed-by: Puranjay Mohan <puranjay@kernel.org>
Signed-off-by: Puranjay Mohan <puranjay@kernel.org>
Link: https://lore.kernel.org/r/20260112201424.816836-2-puranjay@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit af9e89d8dd ]
sync_linked_regs() copies the id of known_reg to reg when propagating
bounds of known_reg to reg using the off of known_reg, but when
known_reg was linked to reg like:
known_reg = reg ; both known_reg and reg get same id
known_reg += 4 ; known_reg gets off = 4, and its id gets BPF_ADD_CONST
now when a call to sync_linked_regs() happens, let's say with the following:
if known_reg >= 10 goto pc+2
known_reg's new bounds are propagated to reg but now reg gets
BPF_ADD_CONST from the copy.
This means if another link to reg is created like:
another_reg = reg ; another_reg should get the id of reg but
assign_scalar_id_before_mov() sees
BPF_ADD_CONST on reg and assigns a new id to it.
As reg has a new id now, known_reg's link to reg is broken. If we find
new bounds for known_reg, they will not be propagated to reg.
This can be seen in the selftest added in the next commit:
0: (85) call bpf_get_prandom_u32#7 ; R0=scalar()
1: (57) r0 &= 255 ; R0=scalar(smin=smin32=0,smax=umax=smax32=umax32=255,var_off=(0x0; 0xff))
2: (bf) r1 = r0 ; R0=scalar(id=1,smin=smin32=0,smax=umax=smax32=umax32=255,var_off=(0x0; 0xff)) R1=scalar(id=1,smin=smin32=0,smax=umax=smax32=umax32=255,var_off=(0x0; 0xff))
3: (07) r1 += 4 ; R1=scalar(id=1+4,smin=umin=smin32=umin32=4,smax=umax=smax32=umax32=259,var_off=(0x0; 0x1ff))
4: (a5) if r1 < 0xa goto pc+4 ; R1=scalar(id=1+4,smin=umin=smin32=umin32=10,smax=umax=smax32=umax32=259,var_off=(0x0; 0x1ff))
5: (bf) r2 = r0 ; R0=scalar(id=2,smin=umin=smin32=umin32=6,smax=umax=smax32=umax32=255) R2=scalar(id=2,smin=umin=smin32=umin32=6,smax=umax=smax32=umax32=255)
6: (a5) if r1 < 0xe goto pc+2 ; R1=scalar(id=1+4,smin=umin=smin32=umin32=14,smax=umax=smax32=umax32=259,var_off=(0x0; 0x1ff))
7: (35) if r0 >= 0xa goto pc+1 ; R0=scalar(id=2,smin=umin=smin32=umin32=6,smax=umax=smax32=umax32=9,var_off=(0x0; 0xf))
8: (37) r0 /= 0
div by zero
When 4 is verified, r1's bounds are propagated to r0 but r0 also gets
BPF_ADD_CONST (bug).
When 5 is verified, r0 gets a new id (2) and its link with r1 is broken.
After 6 we know r1 has bounds [14, 259] and therefore r0 should have
bounds [10, 255], therefore the branch at 7 is always taken. But because
r0's id was changed to 2, r1's new bounds are not propagated to r0.
The verifier still thinks r0 has bounds [6, 255] before 7 and execution
can reach div by zero.
Fix this by preserving id in sync_linked_regs() like off and subreg_def.
Fixes: 98d7ca374b ("bpf: Track delta between "linked" registers.")
Signed-off-by: Puranjay Mohan <puranjay@kernel.org>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260115151143.1344724-2-puranjay@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit b0c8e6d3d8 ]
The usage pattern for widen_imprecise_scalars() looks as follows:
prev_st = find_prev_entry(env, ...);
queued_st = push_stack(...);
widen_imprecise_scalars(env, prev_st, queued_st);
Where prev_st is an ancestor of the queued_st in the explored states
tree. This ancestor is not guaranteed to have same allocated stack
depth as queued_st. E.g. in the following case:
def main():
for i in 1..2:
foo(i) // same callsite, differnt param
def foo(i):
if i == 1:
use 128 bytes of stack
iterator based loop
Here, for a second 'foo' call prev_st->allocated_stack is 128,
while queued_st->allocated_stack is much smaller.
widen_imprecise_scalars() needs to take this into account and avoid
accessing bpf_verifier_state->frame[*]->stack out of bounds.
Fixes: 2793a8b015 ("bpf: exact states comparison for iterator convergence checks")
Reported-by: Emil Tsalapatis <emil@etsalapatis.com>
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20251114025730.772723-1-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit f41345f47f ]
In the following toy program (reg states minimized for readability), R0
and R1 always have different values at instruction 6. This is obvious
when reading the program but cannot be guessed from ranges alone as
they overlap (R0 in [0; 0xc0000000], R1 in [1024; 0xc0000400]).
0: call bpf_get_prandom_u32#7 ; R0_w=scalar()
1: w0 = w0 ; R0_w=scalar(var_off=(0x0; 0xffffffff))
2: r0 >>= 30 ; R0_w=scalar(var_off=(0x0; 0x3))
3: r0 <<= 30 ; R0_w=scalar(var_off=(0x0; 0xc0000000))
4: r1 = r0 ; R1_w=scalar(var_off=(0x0; 0xc0000000))
5: r1 += 1024 ; R1_w=scalar(var_off=(0x400; 0xc0000000))
6: if r1 != r0 goto pc+1
Looking at tnums however, we can deduce that R1 is always different from
R0 because their tnums don't agree on known bits. This patch uses this
logic to improve is_scalar_branch_taken in case of BPF_JEQ and BPF_JNE.
This change has a tiny impact on complexity, which was measured with
the Cilium complexity CI test. That test covers 72 programs with
various build and load time configurations for a total of 970 test
cases. For 80% of test cases, the patch has no impact. On the other
test cases, the patch decreases complexity by only 0.08% on average. In
the best case, the verifier needs to walk 3% less instructions and, in
the worst case, 1.5% more. Overall, the patch has a small positive
impact, especially for our largest programs.
Signed-off-by: Paul Chaignon <paul.chaignon@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/be3ee70b6e489c49881cb1646114b1d861b5c334.1755694147.git.paul.chaignon@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit a76ab5731e ]
Private stack will be allocated with percpu allocator in jit time.
To avoid complexity at runtime, only one copy of private stack is
available per cpu per prog. So runtime recursion check is necessary
to avoid stack corruption.
Current private stack only supports kprobe/perf_event/tp/raw_tp
which has recursion check in the kernel, and prog types that use
bpf trampoline recursion check. For trampoline related prog types,
currently only tracing progs have recursion checking.
To avoid complexity, all async_cb subprogs use normal kernel stack
including those subprogs used by both main prog subtree and async_cb
subtree. Any prog having tail call also uses kernel stack.
To avoid jit penalty with private stack support, a subprog stack
size threshold is set such that only if the stack size is no less
than the threshold, private stack is supported. The current threshold
is 64 bytes. This avoids jit penality if the stack usage is small.
A useless 'continue' is also removed from a loop in func
check_max_stack_depth().
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20241112163907.2223839-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Stable-dep-of: 881a9c9cb7 ("bpf: Do not audit capability check in do_jit()")
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 55c0ced59f ]
When verifying BPF programs, the check_alu_op() function validates
instructions with ALU operations. The 'offset' field in these
instructions is a signed 16-bit integer.
The existing check 'insn->off > 1' was intended to ensure the offset is
either 0, or 1 for BPF_MOD/BPF_DIV. However, because 'insn->off' is
signed, this check incorrectly accepts all negative values (e.g., -1).
This commit tightens the validation by changing the condition to
'(insn->off != 0 && insn->off != 1)'. This ensures that any value
other than the explicitly permitted 0 and 1 is rejected, hardening the
verifier against malformed BPF programs.
Co-developed-by: Shenghao Yuan <shenghaoyuan0928@163.com>
Signed-off-by: Shenghao Yuan <shenghaoyuan0928@163.com>
Co-developed-by: Tianci Cao <ziye@zju.edu.cn>
Signed-off-by: Tianci Cao <ziye@zju.edu.cn>
Signed-off-by: Yazhou Tang <tangyazhou518@outlook.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Fixes: ec0e2da95f ("bpf: Support new signed div/mod instructions.")
Link: https://lore.kernel.org/r/tencent_70D024BAE70A0A309A4781694C7B764B0608@qq.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit e25ddfb388 ]
When enable CONFIG_PREEMPT_RT, the kernel will warn when run timer
selftests by './test_progs -t timer':
BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:48
In order to avoid such warning, reject bpf_timer in verifier when
PREEMPT_RT is enabled.
Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
Link: https://lore.kernel.org/r/20250910125740.52172-2-leon.hwang@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 5534e58f2e ]
When reg->type is CONST_PTR_TO_MAP, it can not be null. However the
verifier explores the branches under rX == 0 in check_cond_jmp_op()
even if reg->type is CONST_PTR_TO_MAP, because it was not checked for
in reg_not_null().
Fix this by adding CONST_PTR_TO_MAP to the set of types that are
considered non nullable in reg_not_null().
An old "unpriv: cmp map pointer with zero" selftest fails with this
change, because now early out correctly triggers in
check_cond_jmp_op(), making the verification to pass.
In practice verifier may allow pointer to null comparison in unpriv,
since in many cases the relevant branch and comparison op are removed
as dead code. So change the expected test result to __success_unpriv.
Signed-off-by: Ihor Solodrai <isolodrai@meta.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250609183024.359974-2-isolodrai@meta.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 6279846b9b ]
Syzbot reported a kernel warning due to a range invariant violation on
the following BPF program.
0: call bpf_get_netns_cookie
1: if r0 == 0 goto <exit>
2: if r0 & Oxffffffff goto <exit>
The issue is on the path where we fall through both jumps.
That path is unreachable at runtime: after insn 1, we know r0 != 0, but
with the sign extension on the jset, we would only fallthrough insn 2
if r0 == 0. Unfortunately, is_branch_taken() isn't currently able to
figure this out, so the verifier walks all branches. The verifier then
refines the register bounds using the second condition and we end
up with inconsistent bounds on this unreachable path:
1: if r0 == 0 goto <exit>
r0: u64=[0x1, 0xffffffffffffffff] var_off=(0, 0xffffffffffffffff)
2: if r0 & 0xffffffff goto <exit>
r0 before reg_bounds_sync: u64=[0x1, 0xffffffffffffffff] var_off=(0, 0)
r0 after reg_bounds_sync: u64=[0x1, 0] var_off=(0, 0)
Improving the range refinement for JSET to cover all cases is tricky. We
also don't expect many users to rely on JSET given LLVM doesn't generate
those instructions. So instead of improving the range refinement for
JSETs, Eduard suggested we forget the ranges whenever we're narrowing
tnums after a JSET. This patch implements that approach.
Reported-by: syzbot+c711ce17dd78e5d4fdcf@syzkaller.appspotmail.com
Suggested-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Paul Chaignon <paul.chaignon@gmail.com>
Link: https://lore.kernel.org/r/9d4fd6432a095d281f815770608fdcd16028ce0b.1752171365.git.paul.chaignon@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 96a30e469c ]
Instead of allocating and copying instruction history each time we
enqueue child verifier state, switch to a model where we use one common
dynamically sized array of instruction history entries across all states.
The key observation for proving this is correct is that instruction
history is only relevant while state is active, which means it either is
a current state (and thus we are actively modifying instruction history
and no other state can interfere with us) or we are checkpointed state
with some children still active (either enqueued or being current).
In the latter case our portion of instruction history is finalized and
won't change or grow, so as long as we keep it immutable until the state
is finalized, we are good.
Now, when state is finalized and is put into state hash for potentially
future pruning lookups, instruction history is not used anymore. This is
because instruction history is only used by precision marking logic, and
we never modify precision markings for finalized states.
So, instead of each state having its own small instruction history, we
keep a global dynamically-sized instruction history, where each state in
current DFS path from root to active state remembers its portion of
instruction history. Current state can append to this history, but
cannot modify any of its parent histories.
Async callback state enqueueing, while logically detached from parent
state, still is part of verification backtracking tree, so has to follow
the same schema as normal state checkpoints.
Because the insn_hist array can be grown through realloc, states don't
keep pointers, they instead maintain two indices, [start, end), into
global instruction history array. End is exclusive index, so
`start == end` means there is no relevant instruction history.
This eliminates a lot of allocations and minimizes overall memory usage.
For instance, running a worst-case test from [0] (but without the
heuristics-based fix [1]), it took 12.5 minutes until we get -ENOMEM.
With the changes in this patch the whole test succeeds in 10 minutes
(very slow, so heuristics from [1] is important, of course).
To further validate correctness, veristat-based comparison was performed for
Meta production BPF objects and BPF selftests objects. In both cases there
were no differences *at all* in terms of verdict or instruction and state
counts, providing a good confidence in the change.
Having this low-memory-overhead solution of keeping dynamic
per-instruction history cheaply opens up some new possibilities, like
keeping extra information for literally every single validated
instruction. This will be used for simplifying precision backpropagation
logic in follow up patches.
[0] https://lore.kernel.org/bpf/20241029172641.1042523-2-eddyz87@gmail.com/
[1] https://lore.kernel.org/bpf/20241029172641.1042523-1-eddyz87@gmail.com/
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20241115001303.277272-1-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Stable-dep-of: e2d2115e56 ("bpf: Do not include stack ptr register in precision backtracking bookkeeping")
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit d519594ee2 ]
Currently, add_kfunc_call() is only invoked once before the main
verification loop. Therefore, the verifier could not find the
bpf_kfunc_btf_tab of a new kfunc call which is not seen in user defined
struct_ops operators but introduced in gen_prologue or gen_epilogue
during do_misc_fixup(). Fix this by searching kfuncs in the patching
instruction buffer and add them to prog->aux->kfunc_tab.
Signed-off-by: Amery Hung <amery.hung@bytedance.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20250225233545.285481-1-ameryhung@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit cfe816d469 ]
If we attach fexit/fmod_ret to __noreturn functions, it will cause an
issue that the bpf trampoline image will be left over even if the bpf
link has been destroyed. Take attaching do_exit() with fexit for example.
The fexit works as follows,
bpf_trampoline
+ __bpf_tramp_enter
+ percpu_ref_get(&tr->pcref);
+ call do_exit()
+ __bpf_tramp_exit
+ percpu_ref_put(&tr->pcref);
Since do_exit() never returns, the refcnt of the trampoline image is
never decremented, preventing it from being freed. That can be verified
with as follows,
$ bpftool link show <<<< nothing output
$ grep "bpf_trampoline_[0-9]" /proc/kallsyms
ffffffffc04cb000 t bpf_trampoline_6442526459 [bpf] <<<< leftover
In this patch, all functions annotated with __noreturn are rejected, except
for the following cases:
- Functions that result in a system reboot, such as panic,
machine_real_restart and rust_begin_unwind
- Functions that are never executed by tasks, such as rest_init and
cpu_startup_entry
- Functions implemented in assembly, such as rewind_stack_and_make_dead and
xen_cpu_bringup_again, lack an associated BTF ID.
With this change, attaching fexit probes to functions like do_exit() will
be rejected.
$ ./fexit
libbpf: prog 'fexit': BPF program load failed: -EINVAL
libbpf: prog 'fexit': -- BEGIN PROG LOAD LOG --
Attaching fexit/fmod_ret to __noreturn functions is rejected.
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Link: https://lore.kernel.org/r/20250318114447.75484-2-laoar.shao@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit ac6542ad92 upstream.
bpf_prog_aux->func field might be NULL if program does not have
subprograms except for main sub-program. The fixed commit does
bpf_prog_aux->func access unconditionally, which might lead to null
pointer dereference.
The bug could be triggered by replacing the following BPF program:
SEC("tc")
int main_changes(struct __sk_buff *sk)
{
bpf_skb_pull_data(sk, 0);
return 0;
}
With the following BPF program:
SEC("freplace")
long changes_pkt_data(struct __sk_buff *sk)
{
return bpf_skb_pull_data(sk, 0);
}
bpf_prog_aux instance itself represents the main sub-program,
use this property to fix the bug.
Fixes: 81f6d0530b ("bpf: check changes_pkt_data property for extension programs")
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/r/202412111822.qGw6tOyB-lkp@intel.com/
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20241212070711.427443-1-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 81f6d0530b upstream.
When processing calls to global sub-programs, verifier decides whether
to invalidate all packet pointers in current state depending on the
changes_pkt_data property of the global sub-program.
Because of this, an extension program replacing a global sub-program
must be compatible with changes_pkt_data property of the sub-program
being replaced.
This commit:
- adds changes_pkt_data flag to struct bpf_prog_aux:
- this flag is set in check_cfg() for main sub-program;
- in jit_subprogs() for other sub-programs;
- modifies bpf_check_attach_btf_id() to check changes_pkt_data flag;
- moves call to check_attach_btf_id() after the call to check_cfg(),
because it needs changes_pkt_data flag to be set:
bpf_check:
... ...
- check_attach_btf_id resolve_pseudo_ldimm64
resolve_pseudo_ldimm64 --> bpf_prog_is_offloaded
bpf_prog_is_offloaded check_cfg
check_cfg + check_attach_btf_id
... ...
The following fields are set by check_attach_btf_id():
- env->ops
- prog->aux->attach_btf_trace
- prog->aux->attach_func_name
- prog->aux->attach_func_proto
- prog->aux->dst_trampoline
- prog->aux->mod
- prog->aux->saved_dst_attach_type
- prog->aux->saved_dst_prog_type
- prog->expected_attach_type
Neither of these fields are used by resolve_pseudo_ldimm64() or
bpf_prog_offload_verifier_prep() (for netronome and netdevsim
drivers), so the reordering is safe.
Suggested-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20241210041100.1898468-6-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
[ shung-hsi.yu: both jits_use_priv_stack and priv_stack_requested fields are
missing from context because "bpf: Support private stack for bpf progs" series
is not present.]
Signed-off-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 51081a3f25 upstream.
When processing calls to certain helpers, verifier invalidates all
packet pointers in a current state. For example, consider the
following program:
__attribute__((__noinline__))
long skb_pull_data(struct __sk_buff *sk, __u32 len)
{
return bpf_skb_pull_data(sk, len);
}
SEC("tc")
int test_invalidate_checks(struct __sk_buff *sk)
{
int *p = (void *)(long)sk->data;
if ((void *)(p + 1) > (void *)(long)sk->data_end) return TCX_DROP;
skb_pull_data(sk, 0);
*p = 42;
return TCX_PASS;
}
After a call to bpf_skb_pull_data() the pointer 'p' can't be used
safely. See function filter.c:bpf_helper_changes_pkt_data() for a list
of such helpers.
At the moment verifier invalidates packet pointers when processing
helper function calls, and does not traverse global sub-programs when
processing calls to global sub-programs. This means that calls to
helpers done from global sub-programs do not invalidate pointers in
the caller state. E.g. the program above is unsafe, but is not
rejected by verifier.
This commit fixes the omission by computing field
bpf_subprog_info->changes_pkt_data for each sub-program before main
verification pass.
changes_pkt_data should be set if:
- subprogram calls helper for which bpf_helper_changes_pkt_data
returns true;
- subprogram calls a global function,
for which bpf_subprog_info->changes_pkt_data should be set.
The verifier.c:check_cfg() pass is modified to compute this
information. The commit relies on depth first instruction traversal
done by check_cfg() and absence of recursive function calls:
- check_cfg() would eventually visit every call to subprogram S in a
state when S is fully explored;
- when S is fully explored:
- every direct helper call within S is explored
(and thus changes_pkt_data is set if needed);
- every call to subprogram S1 called by S was visited with S1 fully
explored (and thus S inherits changes_pkt_data from S1).
The downside of such approach is that dead code elimination is not
taken into account: if a helper call inside global function is dead
because of current configuration, verifier would conservatively assume
that the call occurs for the purpose of the changes_pkt_data
computation.
Reported-by: Nick Zavaritsky <mejedi@gmail.com>
Closes: https://lore.kernel.org/bpf/0498CA22-5779-4767-9C0C-A9515CEA711F@gmail.com/
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20241210041100.1898468-4-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 6ebc5030e0 ]
may_goto uses an additional 8 bytes on the stack, which causes the
interpreters[] array to go out of bounds when calculating index by
stack_size.
1. If a BPF program is rewritten, re-evaluate the stack size. For non-JIT
cases, reject loading directly.
2. For non-JIT cases, calculating interpreters[idx] may still cause
out-of-bounds array access, and just warn about it.
3. For jit_requested cases, the execution of bpf_func also needs to be
warned. So move the definition of function __bpf_prog_ret0_warn out of
the macro definition CONFIG_BPF_JIT_ALWAYS_ON.
Reported-by: syzbot+d2a2c639d03ac200a4f1@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/bpf/0000000000000f823606139faa5d@google.com/
Fixes: 011832b97b ("bpf: Introduce may_goto instruction")
Signed-off-by: Jiayuan Chen <mrpre@163.com>
Link: https://lore.kernel.org/r/20250214091823.46042-2-mrpre@163.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit b238e187b4 ]
Use BPF helper number instead of function pointer in
bpf_helper_changes_pkt_data(). This would simplify usage of this
function in verifier.c:check_cfg() (in a follow-up patch),
where only helper number is easily available and there is no real need
to lookup helper proto.
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20241210041100.1898468-3-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Stable-dep-of: 1a4607ffba ("bpf: consider that tail calls invalidate packet pointers")
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit bd74e238ae ]
Andrii spotted that process_dynptr_func's rejection of incorrect
argument register type will print an error string where argument numbers
are not zero-indexed, unlike elsewhere in the verifier. Fix this by
subtracting 1 from regno. The same scenario exists for iterator
messages. Fix selftest error strings that match on the exact argument
number while we're at it to ensure clean bisection.
Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20241203002235.3776418-1-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 23579010cf ]
On x86-64 calling bpf_get_smp_processor_id() in a kernel with CONFIG_SMP
disabled can trigger the following bug, as pcpu_hot is unavailable:
[ 8.471774] BUG: unable to handle page fault for address: 00000000936a290c
[ 8.471849] #PF: supervisor read access in kernel mode
[ 8.471881] #PF: error_code(0x0000) - not-present page
Fix by inlining a return 0 in the !CONFIG_SMP case.
Fixes: 1ae6921009 ("bpf: inline bpf_get_smp_processor_id() helper")
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20241217195813.622568-1-arighi@nvidia.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit c00d738e16 upstream.
This patch reverts commit
cb4158ce8e ("bpf: Mark raw_tp arguments with PTR_MAYBE_NULL"). The
patch was well-intended and meant to be as a stop-gap fixing branch
prediction when the pointer may actually be NULL at runtime. Eventually,
it was supposed to be replaced by an automated script or compiler pass
detecting possibly NULL arguments and marking them accordingly.
However, it caused two main issues observed for production programs and
failed to preserve backwards compatibility. First, programs relied on
the verifier not exploring == NULL branch when pointer is not NULL, thus
they started failing with a 'dereference of scalar' error. Next,
allowing raw_tp arguments to be modified surfaced the warning in the
verifier that warns against reg->off when PTR_MAYBE_NULL is set.
More information, context, and discusson on both problems is available
in [0]. Overall, this approach had several shortcomings, and the fixes
would further complicate the verifier's logic, and the entire masking
scheme would have to be removed eventually anyway.
Hence, revert the patch in preparation of a better fix avoiding these
issues to replace this commit.
[0]: https://lore.kernel.org/bpf/20241206161053.809580-1-memxor@gmail.com
Reported-by: Manu Bretelle <chantra@meta.com>
Fixes: cb4158ce8e ("bpf: Mark raw_tp arguments with PTR_MAYBE_NULL")
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20241213221929.3495062-2-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit b0e66977dc ]
When CAP_PERFMON and CAP_SYS_ADMIN (allow_ptr_leaks) are disabled, the
verifier aims to reject partial overwrite on an 8-byte stack slot that
contains a spilled pointer.
However, in such a scenario, it rejects all partial stack overwrites as
long as the targeted stack slot is a spilled register, because it does
not check if the stack slot is a spilled pointer.
Incomplete checks will result in the rejection of valid programs, which
spill narrower scalar values onto scalar slots, as shown below.
0: R1=ctx() R10=fp0
; asm volatile ( @ repro.bpf.c:679
0: (7a) *(u64 *)(r10 -8) = 1 ; R10=fp0 fp-8_w=1
1: (62) *(u32 *)(r10 -8) = 1
attempt to corrupt spilled pointer on stack
processed 2 insns (limit 1000000) max_states_per_insn 0 total_states 0 peak_states 0 mark_read 0.
Fix this by expanding the check to not consider spilled scalar registers
when rejecting the write into the stack.
Previous discussion on this patch is at link [0].
[0]: https://lore.kernel.org/bpf/20240403202409.2615469-1-tao.lyu@epfl.ch
Fixes: ab125ed3ec ("bpf: fix check for attempt to corrupt spilled pointer")
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Tao Lyu <tao.lyu@epfl.ch>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20241204044757.1483141-3-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 69772f509e ]
Inside mark_stack_slot_misc, we should not upgrade STACK_INVALID to
STACK_MISC when allow_ptr_leaks is false, since invalid contents
shouldn't be read unless the program has the relevant capabilities.
The relaxation only makes sense when env->allow_ptr_leaks is true.
However, such conversion in privileged mode becomes unnecessary, as
invalid slots can be read without being upgraded to STACK_MISC.
Currently, the condition is inverted (i.e. checking for true instead of
false), simply remove it to restore correct behavior.
Fixes: eaf18febd6 ("bpf: preserve STACK_ZERO slots on partial reg spills")
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Reported-by: Tao Lyu <tao.lyu@epfl.ch>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20241204044757.1483141-2-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 12659d2861 ]
Currently, KF_ARG_PTR_TO_ITER handling missed checking the reg->type and
ensuring it is PTR_TO_STACK. Instead of enforcing this in the caller of
process_iter_arg, move the check into it instead so that all callers
will gain the check by default. This is similar to process_dynptr_func.
An existing selftest in verifier_bits_iter.c fails due to this change,
but it's because it was passing a NULL pointer into iter_next helper and
getting an error further down the checks, but probably meant to pass an
uninitialized iterator on the stack (as is done in the subsequent test
below it). We will gain coverage for non-PTR_TO_STACK arguments in later
patches hence just change the declaration to zero-ed stack object.
Fixes: 06accc8779 ("bpf: add support for open-coded iterator loops")
Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Tao Lyu <tao.lyu@epfl.ch>
[ Kartikeya: move check into process_iter_arg, rewrite commit log ]
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20241203000238.3602922-2-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit cb4158ce8e ]
Arguments to a raw tracepoint are tagged as trusted, which carries the
semantics that the pointer will be non-NULL. However, in certain cases,
a raw tracepoint argument may end up being NULL. More context about this
issue is available in [0].
Thus, there is a discrepancy between the reality, that raw_tp arguments
can actually be NULL, and the verifier's knowledge, that they are never
NULL, causing explicit NULL checks to be deleted, and accesses to such
pointers potentially crashing the kernel.
To fix this, mark raw_tp arguments as PTR_MAYBE_NULL, and then special
case the dereference and pointer arithmetic to permit it, and allow
passing them into helpers/kfuncs; these exceptions are made for raw_tp
programs only. Ensure that we don't do this when ref_obj_id > 0, as in
that case this is an acquired object and doesn't need such adjustment.
The reason we do mask_raw_tp_trusted_reg logic is because other will
recheck in places whether the register is a trusted_reg, and then
consider our register as untrusted when detecting the presence of the
PTR_MAYBE_NULL flag.
To allow safe dereference, we enable PROBE_MEM marking when we see loads
into trusted pointers with PTR_MAYBE_NULL.
While trusted raw_tp arguments can also be passed into helpers or kfuncs
where such broken assumption may cause issues, a future patch set will
tackle their case separately, as PTR_TO_BTF_ID (without PTR_TRUSTED) can
already be passed into helpers and causes similar problems. Thus, they
are left alone for now.
It is possible that these checks also permit passing non-raw_tp args
that are trusted PTR_TO_BTF_ID with null marking. In such a case,
allowing dereference when pointer is NULL expands allowed behavior, so
won't regress existing programs, and the case of passing these into
helpers is the same as above and will be dealt with later.
Also update the failure case in tp_btf_nullable selftest to capture the
new behavior, as the verifier will no longer cause an error when
directly dereference a raw tracepoint argument marked as __nullable.
[0]: https://lore.kernel.org/bpf/ZrCZS6nisraEqehw@jlelli-thinkpadt14gen4.remote.csb
Reviewed-by: Jiri Olsa <jolsa@kernel.org>
Reported-by: Juri Lelli <juri.lelli@redhat.com>
Tested-by: Juri Lelli <juri.lelli@redhat.com>
Fixes: 3f00c52393 ("bpf: Allow trusted pointers to be passed to KF_TRUSTED_ARGS kfuncs")
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20241104171959.2938862-2-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 46f7ed32f7 ]
There are three situations when a program logically exits and transfers
control to the kernel or another program: bpf_throw, BPF_EXIT, and tail
calls. The former two check for any lingering locks and references, but
tail calls currently do not. Expand the checks to check for spin locks,
RCU read sections and preempt disabled sections.
Spin locks are indirectly preventing tail calls as function calls are
disallowed, but the checks for preemption and RCU are more relaxed,
hence ensure tail calls are prevented in their presence.
Fixes: 9bb00b2895 ("bpf: Add kfunc bpf_rcu_read_lock/unlock()")
Fixes: fc7566ad0a ("bpf: Introduce bpf_preempt_[disable,enable] kfuncs")
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20241103225940.1408302-2-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
A specifically crafted program might trick verifier into growing very
long jump history within a single bpf_verifier_state instance.
Very long jump history makes mark_chain_precision() unreasonably slow,
especially in case if verifier processes a loop.
Mitigate this by forcing new state in is_state_visited() in case if
current state's jump history is too long.
Use same constant as in `skip_inf_loop_check`, but multiply it by
arbitrarily chosen value 2 to account for jump history containing not
only information about jumps, but also information about stack access.
For an example of problematic program consider the code below,
w/o this patch the example is processed by verifier for ~15 minutes,
before failing to allocate big-enough chunk for jmp_history.
0: r7 = *(u16 *)(r1 +0);"
1: r7 += 0x1ab064b9;"
2: if r7 & 0x702000 goto 1b;
3: r7 &= 0x1ee60e;"
4: r7 += r1;"
5: if r7 s> 0x37d2 goto +0;"
6: r0 = 0;"
7: exit;"
Perf profiling shows that most of the time is spent in
mark_chain_precision() ~95%.
The easiest way to explain why this program causes problems is to
apply the following patch:
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 0c216e71cec7..4b4823961abe 100644
\--- a/include/linux/bpf.h
\+++ b/include/linux/bpf.h
\@@ -1926,7 +1926,7 @@ struct bpf_array {
};
};
-#define BPF_COMPLEXITY_LIMIT_INSNS 1000000 /* yes. 1M insns */
+#define BPF_COMPLEXITY_LIMIT_INSNS 256 /* yes. 1M insns */
#define MAX_TAIL_CALL_CNT 33
/* Maximum number of loops for bpf_loop and bpf_iter_num.
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index f514247ba8ba..75e88be3bb3e 100644
\--- a/kernel/bpf/verifier.c
\+++ b/kernel/bpf/verifier.c
\@@ -18024,8 +18024,13 @@ static int is_state_visited(struct bpf_verifier_env *env, int insn_idx)
skip_inf_loop_check:
if (!force_new_state &&
env->jmps_processed - env->prev_jmps_processed < 20 &&
- env->insn_processed - env->prev_insn_processed < 100)
+ env->insn_processed - env->prev_insn_processed < 100) {
+ verbose(env, "is_state_visited: suppressing checkpoint at %d, %d jmps processed, cur->jmp_history_cnt is %d\n",
+ env->insn_idx,
+ env->jmps_processed - env->prev_jmps_processed,
+ cur->jmp_history_cnt);
add_new_state = false;
+ }
goto miss;
}
/* If sl->state is a part of a loop and this loop's entry is a part of
\@@ -18142,6 +18147,9 @@ static int is_state_visited(struct bpf_verifier_env *env, int insn_idx)
if (!add_new_state)
return 0;
+ verbose(env, "is_state_visited: new checkpoint at %d, resetting env->jmps_processed\n",
+ env->insn_idx);
+
/* There were no equivalent states, remember the current one.
* Technically the current state is not proven to be safe yet,
* but it will either reach outer most bpf_exit (which means it's safe)
And observe verification log:
...
is_state_visited: new checkpoint at 5, resetting env->jmps_processed
5: R1=ctx() R7=ctx(...)
5: (65) if r7 s> 0x37d2 goto pc+0 ; R7=ctx(...)
6: (b7) r0 = 0 ; R0_w=0
7: (95) exit
from 5 to 6: R1=ctx() R7=ctx(...) R10=fp0
6: R1=ctx() R7=ctx(...) R10=fp0
6: (b7) r0 = 0 ; R0_w=0
7: (95) exit
is_state_visited: suppressing checkpoint at 1, 3 jmps processed, cur->jmp_history_cnt is 74
from 2 to 1: R1=ctx() R7_w=scalar(...) R10=fp0
1: R1=ctx() R7_w=scalar(...) R10=fp0
1: (07) r7 += 447767737
is_state_visited: suppressing checkpoint at 2, 3 jmps processed, cur->jmp_history_cnt is 75
2: R7_w=scalar(...)
2: (45) if r7 & 0x702000 goto pc-2
... mark_precise 152 steps for r7 ...
2: R7_w=scalar(...)
is_state_visited: suppressing checkpoint at 1, 4 jmps processed, cur->jmp_history_cnt is 75
1: (07) r7 += 447767737
is_state_visited: suppressing checkpoint at 2, 4 jmps processed, cur->jmp_history_cnt is 76
2: R7_w=scalar(...)
2: (45) if r7 & 0x702000 goto pc-2
...
BPF program is too large. Processed 257 insn
The log output shows that checkpoint at label (1) is never created,
because it is suppressed by `skip_inf_loop_check` logic:
a. When 'if' at (2) is processed it pushes a state with insn_idx (1)
onto stack and proceeds to (3);
b. At (5) checkpoint is created, and this resets
env->{jmps,insns}_processed.
c. Verification proceeds and reaches `exit`;
d. State saved at step (a) is popped from stack and is_state_visited()
considers if checkpoint needs to be added, but because
env->{jmps,insns}_processed had been just reset at step (b)
the `skip_inf_loop_check` logic forces `add_new_state` to false.
e. Verifier proceeds with current state, which slowly accumulates
more and more entries in the jump history.
The accumulation of entries in the jump history is a problem because
of two factors:
- it eventually exhausts memory available for kmalloc() allocation;
- mark_chain_precision() traverses the jump history of a state,
meaning that if `r7` is marked precise, verifier would iterate
ever growing jump history until parent state boundary is reached.
(note: the log also shows a REG INVARIANTS VIOLATION warning
upon jset processing, but that's another bug to fix).
With this patch applied, the example above is rejected by verifier
under 1s of time, reaching 1M instructions limit.
The program is a simplified reproducer from syzbot report.
Previous discussion could be found at [1].
The patch does not cause any changes in verification performance,
when tested on selftests from veristat.cfg and cilium programs taken
from [2].
[1] https://lore.kernel.org/bpf/20241009021254.2805446-1-eddyz87@gmail.com/
[2] https://github.com/anakryiko/cilium
Changelog:
- v1 -> v2:
- moved patch to bpf tree;
- moved force_new_state variable initialization after declaration and
shortened the comment.
v1: https://lore.kernel.org/bpf/20241018020307.1766906-1-eddyz87@gmail.com/
Fixes: 2589726d12 ("bpf: introduce bounded loops")
Reported-by: syzbot+7e46cdef14bf496a3ab4@syzkaller.appspotmail.com
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20241029172641.1042523-1-eddyz87@gmail.com
Closes: https://lore.kernel.org/bpf/670429f6.050a0220.49194.0517.GAE@google.com/
Lonial reported an issue in the BPF verifier where check_mem_size_reg()
has the following code:
if (!tnum_is_const(reg->var_off))
/* For unprivileged variable accesses, disable raw
* mode so that the program is required to
* initialize all the memory that the helper could
* just partially fill up.
*/
meta = NULL;
This means that writes are not checked when the register containing the
size of the passed buffer has not a fixed size. Through this bug, a BPF
program can write to a map which is marked as read-only, for example,
.rodata global maps.
The problem is that MEM_UNINIT's initial meaning that "the passed buffer
to the BPF helper does not need to be initialized" which was added back
in commit 435faee1aa ("bpf, verifier: add ARG_PTR_TO_RAW_STACK type")
got overloaded over time with "the passed buffer is being written to".
The problem however is that checks such as the above which were added later
via 06c1c04972 ("bpf: allow helpers access to variable memory") set meta
to NULL in order force the user to always initialize the passed buffer to
the helper. Due to the current double meaning of MEM_UNINIT, this bypasses
verifier write checks to the memory (not boundary checks though) and only
assumes the latter memory is read instead.
Fix this by reverting MEM_UNINIT back to its original meaning, and having
MEM_WRITE as an annotation to BPF helpers in order to then trigger the
BPF verifier checks for writing to memory.
Some notes: check_arg_pair_ok() ensures that for ARG_CONST_SIZE{,_OR_ZERO}
we can access fn->arg_type[arg - 1] since it must contain a preceding
ARG_PTR_TO_MEM. For check_mem_reg() the meta argument can be removed
altogether since we do check both BPF_READ and BPF_WRITE. Same for the
equivalent check_kfunc_mem_size_reg().
Fixes: 7b3552d3f9 ("bpf: Reject writes for PTR_TO_MAP_KEY in check_helper_mem_access")
Fixes: 97e6d7dab1 ("bpf: Check PTR_TO_MEM | MEM_RDONLY in check_helper_mem_access")
Fixes: 15baa55ff5 ("bpf/verifier: allow all functions to read user provided context")
Reported-by: Lonial Con <kongln9170@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20241021152809.33343-2-daniel@iogearbox.net
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Nathaniel reported a bug in the linked scalar delta tracking, which can lead
to accepting a program with OOB access. The specific code is related to the
sync_linked_regs() function and the BPF_ADD_CONST flag, which signifies a
constant offset between two scalar registers tracked by the same register id.
The verifier attempts to track "similar" scalars in order to propagate bounds
information learned about one scalar to others. For instance, if r1 and r2
are known to contain the same value, then upon encountering 'if (r1 != 0x1234)
goto xyz', not only does it know that r1 is equal to 0x1234 on the path where
that conditional jump is not taken, it also knows that r2 is.
Additionally, with env->bpf_capable set, the verifier will track scalars
which should be a constant delta apart (if r1 is known to be one greater than
r2, then if r1 is known to be equal to 0x1234, r2 must be equal to 0x1233.)
The code path for the latter in adjust_reg_min_max_vals() is reached when
processing both 32 and 64-bit addition operations. While adjust_reg_min_max_vals()
knows whether dst_reg was produced by a 32 or a 64-bit addition (based on the
alu32 bool), the only information saved in dst_reg is the id of the source
register (reg->id, or'ed by BPF_ADD_CONST) and the value of the constant
offset (reg->off).
Later, the function sync_linked_regs() will attempt to use this information
to propagate bounds information from one register (known_reg) to others,
meaning, for all R in linked_regs, it copies known_reg range (and possibly
adjusting delta) into R for the case of R->id == known_reg->id.
For the delta adjustment, meaning, matching reg->id with BPF_ADD_CONST, the
verifier adjusts the register as reg = known_reg; reg += delta where delta
is computed as (s32)reg->off - (s32)known_reg->off and placed as a scalar
into a fake_reg to then simulate the addition of reg += fake_reg. This is
only correct, however, if the value in reg was created by a 64-bit addition.
When reg contains the result of a 32-bit addition operation, its upper 32
bits will always be zero. sync_linked_regs() on the other hand, may cause
the verifier to believe that the addition between fake_reg and reg overflows
into those upper bits. For example, if reg was generated by adding the
constant 1 to known_reg using a 32-bit alu operation, then reg->off is 1
and known_reg->off is 0. If known_reg is known to be the constant 0xFFFFFFFF,
sync_linked_regs() will tell the verifier that reg is equal to the constant
0x100000000. This is incorrect as the actual value of reg will be 0, as the
32-bit addition will wrap around.
Example:
0: (b7) r0 = 0; R0_w=0
1: (18) r1 = 0x80000001; R1_w=0x80000001
3: (37) r1 /= 1; R1_w=scalar()
4: (bf) r2 = r1; R1_w=scalar(id=1) R2_w=scalar(id=1)
5: (bf) r4 = r1; R1_w=scalar(id=1) R4_w=scalar(id=1)
6: (04) w2 += 2147483647; R2_w=scalar(id=1+2147483647,smin=0,smax=umax=0xffffffff,var_off=(0x0; 0xffffffff))
7: (04) w4 += 0 ; R4_w=scalar(id=1+0,smin=0,smax=umax=0xffffffff,var_off=(0x0; 0xffffffff))
8: (15) if r2 == 0x0 goto pc+1
10: R0=0 R1=0xffffffff80000001 R2=0x7fffffff R4=0xffffffff80000001 R10=fp0
What can be seen here is that r1 is copied to r2 and r4, such that {r1,r2,r4}.id
are all the same which later lets sync_linked_regs() to be invoked. Then, in
a next step constants are added with alu32 to r2 and r4, setting their ->off,
as well as id |= BPF_ADD_CONST. Next, the conditional will bind r2 and
propagate ranges to its linked registers. The verifier now believes the upper
32 bits of r4 are r4=0xffffffff80000001, while actually r4=r1=0x80000001.
One approach for a simple fix suitable also for stable is to limit the constant
delta tracking to only 64-bit alu addition. If necessary at some later point,
BPF_ADD_CONST could be split into BPF_ADD_CONST64 and BPF_ADD_CONST32 to avoid
mixing the two under the tradeoff to further complicate sync_linked_regs().
However, none of the added tests from dedf56d775 ("selftests/bpf: Add tests
for add_const") make this necessary at this point, meaning, BPF CI also passes
with just limiting tracking to 64-bit alu addition.
Fixes: 98d7ca374b ("bpf: Track delta between "linked" registers.")
Reported-by: Nathaniel Theis <nathaniel.theis@nccgroup.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/bpf/20241016134913.32249-1-daniel@iogearbox.net
coerce_reg_to_size_sx() updates the register state after a sign-extension
operation. However, there's a bug in the assignment order of the unsigned
min/max values, leading to incorrect truncation:
0: (85) call bpf_get_prandom_u32#7 ; R0_w=scalar()
1: (57) r0 &= 1 ; R0_w=scalar(smin=smin32=0,smax=umax=smax32=umax32=1,var_off=(0x0; 0x1))
2: (07) r0 += 254 ; R0_w=scalar(smin=umin=smin32=umin32=254,smax=umax=smax32=umax32=255,var_off=(0xfe; 0x1))
3: (bf) r0 = (s8)r0 ; R0_w=scalar(smin=smin32=-2,smax=smax32=-1,umin=umin32=0xfffffffe,umax=0xffffffff,var_off=(0xfffffffffffffffe; 0x1))
In the current implementation, the unsigned 32-bit min/max values
(u32_min_value and u32_max_value) are assigned directly from the 64-bit
signed min/max values (s64_min and s64_max):
reg->umin_value = reg->u32_min_value = s64_min;
reg->umax_value = reg->u32_max_value = s64_max;
Due to the chain assigmnent, this is equivalent to:
reg->u32_min_value = s64_min; // Unintended truncation
reg->umin_value = reg->u32_min_value;
reg->u32_max_value = s64_max; // Unintended truncation
reg->umax_value = reg->u32_max_value;
Fixes: 1f9a1ea821 ("bpf: Support new sign-extension load insns")
Reported-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Reported-by: Zac Ecob <zacecob@protonmail.com>
Signed-off-by: Dimitar Kanaliev <dimitar.kanaliev@siteground.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Reviewed-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Link: https://lore.kernel.org/r/20241014121155.92887-2-dimitar.kanaliev@siteground.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The verifier contains a cache for looking up module BTF objects when
calling kfuncs defined in modules. This cache uses a 'struct
bpf_kfunc_btf_tab', which contains a sorted list of BTF objects that
were already seen in the current verifier run, and the BTF objects are
looked up by the offset stored in the relocated call instruction using
bsearch().
The first time a given offset is seen, the module BTF is loaded from the
file descriptor passed in by libbpf, and stored into the cache. However,
there's a bug in the code storing the new entry: it stores a pointer to
the new cache entry, then calls sort() to keep the cache sorted for the
next lookup using bsearch(), and then returns the entry that was just
stored through the stored pointer. However, because sort() modifies the
list of entries in place *by value*, the stored pointer may no longer
point to the right entry, in which case the wrong BTF object will be
returned.
The end result of this is an intermittent bug where, if a BPF program
calls two functions with the same signature in two different modules,
the function from the wrong module may sometimes end up being called.
Whether this happens depends on the order of the calls in the BPF
program (as that affects whether sort() reorders the array of BTF
objects), making it especially hard to track down. Simon, credited as
reporter below, spent significant effort analysing and creating a
reproducer for this issue. The reproducer is added as a selftest in a
subsequent patch.
The fix is straight forward: simply don't use the stored pointer after
calling sort(). Since we already have an on-stack pointer to the BTF
object itself at the point where the function return, just use that, and
populate it from the cache entry in the branch where the lookup
succeeds.
Fixes: 2357672c54 ("bpf: Introduce BPF support for kernel module function calls")
Reported-by: Simon Sundberg <simon.sundberg@kau.se>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/r/20241010-fix-kfunc-btf-caching-for-modules-v2-1-745af6c1af98@redhat.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The kzmalloc call in bpf_check can fail when memory is very fragmented,
which in turn can lead to an OOM kill.
Use kvzmalloc to fall back to vmalloc when memory is too fragmented to
allocate an order 3 sized bpf verifier environment.
Admittedly this is not a very common case, and only happens on systems
where memory has already been squeezed close to the limit, but this does
not seem like much of a hot path, and it's a simple enough fix.
Signed-off-by: Rik van Riel <riel@surriel.com>
Reviewed-by: Shakeel Butt <shakeel.butt@linux.dev>
Link: https://lore.kernel.org/r/20241008170735.16766766@imladris.surriel.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Range propagation must not affect subreg_def marks, otherwise the
following example is rewritten by verifier incorrectly when
BPF_F_TEST_RND_HI32 flag is set:
0: call bpf_ktime_get_ns call bpf_ktime_get_ns
1: r0 &= 0x7fffffff after verifier r0 &= 0x7fffffff
2: w1 = w0 rewrites w1 = w0
3: if w0 < 10 goto +0 --------------> r11 = 0x2f5674a6 (r)
4: r1 >>= 32 r11 <<= 32 (r)
5: r0 = r1 r1 |= r11 (r)
6: exit; if w0 < 0xa goto pc+0
r1 >>= 32
r0 = r1
exit
(or zero extension of w1 at (2) is missing for architectures that
require zero extension for upper register half).
The following happens w/o this patch:
- r0 is marked as not a subreg at (0);
- w1 is marked as subreg at (2);
- w1 subreg_def is overridden at (3) by copy_register_state();
- w1 is read at (5) but mark_insn_zext() does not mark (2)
for zero extension, because w1 subreg_def is not set;
- because of BPF_F_TEST_RND_HI32 flag verifier inserts random
value for hi32 bits of (2) (marked (r));
- this random value is read at (5).
Fixes: 75748837b7 ("bpf: Propagate scalar ranges through register assignments.")
Reported-by: Lonial Con <kongln9170@gmail.com>
Signed-off-by: Lonial Con <kongln9170@gmail.com>
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Closes: https://lore.kernel.org/bpf/7e2aa30a62d740db182c170fdd8f81c596df280d.camel@gmail.com
Link: https://lore.kernel.org/bpf/20240924210844.1758441-1-eddyz87@gmail.com
Pull bpf 'struct fd' updates from Alexei Starovoitov:
"This includes struct_fd BPF changes from Al and Andrii"
* tag 'bpf-next-6.12-struct-fd' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next:
bpf: convert bpf_token_create() to CLASS(fd, ...)
security,bpf: constify struct path in bpf_token_create() LSM hook
bpf: more trivial fdget() conversions
bpf: trivial conversions for fdget()
bpf: switch maps to CLASS(fd, ...)
bpf: factor out fetching bpf_map from FD and adding it to used_maps list
bpf: switch fdget_raw() uses to CLASS(fd_raw, ...)
bpf: convert __bpf_prog_get() to CLASS(fd, ...)
Pull bpf updates from Alexei Starovoitov:
- Introduce '__attribute__((bpf_fastcall))' for helpers and kfuncs with
corresponding support in LLVM.
It is similar to existing 'no_caller_saved_registers' attribute in
GCC/LLVM with a provision for backward compatibility. It allows
compilers generate more efficient BPF code assuming the verifier or
JITs will inline or partially inline a helper/kfunc with such
attribute. bpf_cast_to_kern_ctx, bpf_rdonly_cast,
bpf_get_smp_processor_id are the first set of such helpers.
- Harden and extend ELF build ID parsing logic.
When called from sleepable context the relevants parts of ELF file
will be read to find and fetch .note.gnu.build-id information. Also
harden the logic to avoid TOCTOU, overflow, out-of-bounds problems.
- Improvements and fixes for sched-ext:
- Allow passing BPF iterators as kfunc arguments
- Make the pointer returned from iter_next method trusted
- Fix x86 JIT convergence issue due to growing/shrinking conditional
jumps in variable length encoding
- BPF_LSM related:
- Introduce few VFS kfuncs and consolidate them in
fs/bpf_fs_kfuncs.c
- Enforce correct range of return values from certain LSM hooks
- Disallow attaching to other LSM hooks
- Prerequisite work for upcoming Qdisc in BPF:
- Allow kptrs in program provided structs
- Support for gen_epilogue in verifier_ops
- Important fixes:
- Fix uprobe multi pid filter check
- Fix bpf_strtol and bpf_strtoul helpers
- Track equal scalars history on per-instruction level
- Fix tailcall hierarchy on x86 and arm64
- Fix signed division overflow to prevent INT_MIN/-1 trap on x86
- Fix get kernel stack in BPF progs attached to tracepoint:syscall
- Selftests:
- Add uprobe bench/stress tool
- Generate file dependencies to drastically improve re-build time
- Match JIT-ed and BPF asm with __xlated/__jited keywords
- Convert older tests to test_progs framework
- Add support for RISC-V
- Few fixes when BPF programs are compiled with GCC-BPF backend
(support for GCC-BPF in BPF CI is ongoing in parallel)
- Add traffic monitor
- Enable cross compile and musl libc
* tag 'bpf-next-6.12' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (260 commits)
btf: require pahole 1.21+ for DEBUG_INFO_BTF with default DWARF version
btf: move pahole check in scripts/link-vmlinux.sh to lib/Kconfig.debug
btf: remove redundant CONFIG_BPF test in scripts/link-vmlinux.sh
bpf: Call the missed kfree() when there is no special field in btf
bpf: Call the missed btf_record_free() when map creation fails
selftests/bpf: Add a test case to write mtu result into .rodata
selftests/bpf: Add a test case to write strtol result into .rodata
selftests/bpf: Rename ARG_PTR_TO_LONG test description
selftests/bpf: Fix ARG_PTR_TO_LONG {half-,}uninitialized test
bpf: Zero former ARG_PTR_TO_{LONG,INT} args in case of error
bpf: Improve check_raw_mode_ok test for MEM_UNINIT-tagged types
bpf: Fix helper writes to read-only maps
bpf: Remove truncation test in bpf_strtol and bpf_strtoul helpers
bpf: Fix bpf_strtol and bpf_strtoul helpers for 32bit
selftests/bpf: Add tests for sdiv/smod overflow cases
bpf: Fix a sdiv overflow issue
libbpf: Add bpf_object__token_fd accessor
docs/bpf: Add missing BPF program types to docs
docs/bpf: Add constant values for linkages
bpf: Use fake pt_regs when doing bpf syscall tracepoint tracing
...
When checking malformed helper function signatures, also take other argument
types into account aside from just ARG_PTR_TO_UNINIT_MEM.
This concerns (formerly) ARG_PTR_TO_{INT,LONG} given uninitialized memory can
be passed there, too.
The func proto sanity check goes back to commit 435faee1aa ("bpf, verifier:
add ARG_PTR_TO_RAW_STACK type"), and its purpose was to detect wrong func protos
which had more than just one MEM_UNINIT-tagged type as arguments.
The reason more than one is currently not supported is as we mark stack slots with
STACK_MISC in check_helper_call() in case of raw mode based on meta.access_size to
allow uninitialized stack memory to be passed to helpers when they just write into
the buffer.
Probing for base type as well as MEM_UNINIT tagging ensures that other types do not
get missed (as it used to be the case for ARG_PTR_TO_{INT,LONG}).
Fixes: 57c3bb725a ("bpf: Introduce ARG_PTR_TO_{INT,LONG} arg types")
Reported-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Link: https://lore.kernel.org/r/20240913191754.13290-4-daniel@iogearbox.net
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Lonial found an issue that despite user- and BPF-side frozen BPF map
(like in case of .rodata), it was still possible to write into it from
a BPF program side through specific helpers having ARG_PTR_TO_{LONG,INT}
as arguments.
In check_func_arg() when the argument is as mentioned, the meta->raw_mode
is never set. Later, check_helper_mem_access(), under the case of
PTR_TO_MAP_VALUE as register base type, it assumes BPF_READ for the
subsequent call to check_map_access_type() and given the BPF map is
read-only it succeeds.
The helpers really need to be annotated as ARG_PTR_TO_{LONG,INT} | MEM_UNINIT
when results are written into them as opposed to read out of them. The
latter indicates that it's okay to pass a pointer to uninitialized memory
as the memory is written to anyway.
However, ARG_PTR_TO_{LONG,INT} is a special case of ARG_PTR_TO_FIXED_SIZE_MEM
just with additional alignment requirement. So it is better to just get
rid of the ARG_PTR_TO_{LONG,INT} special cases altogether and reuse the
fixed size memory types. For this, add MEM_ALIGNED to additionally ensure
alignment given these helpers write directly into the args via *<ptr> = val.
The .arg*_size has been initialized reflecting the actual sizeof(*<ptr>).
MEM_ALIGNED can only be used in combination with MEM_FIXED_SIZE annotated
argument types, since in !MEM_FIXED_SIZE cases the verifier does not know
the buffer size a priori and therefore cannot blindly write *<ptr> = val.
Fixes: 57c3bb725a ("bpf: Introduce ARG_PTR_TO_{INT,LONG} arg types")
Reported-by: Lonial Con <kongln9170@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Link: https://lore.kernel.org/r/20240913191754.13290-3-daniel@iogearbox.net
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Zac Ecob reported a problem where a bpf program may cause kernel crash due
to the following error:
Oops: divide error: 0000 [#1] PREEMPT SMP KASAN PTI
The failure is due to the below signed divide:
LLONG_MIN/-1 where LLONG_MIN equals to -9,223,372,036,854,775,808.
LLONG_MIN/-1 is supposed to give a positive number 9,223,372,036,854,775,808,
but it is impossible since for 64-bit system, the maximum positive
number is 9,223,372,036,854,775,807. On x86_64, LLONG_MIN/-1 will
cause a kernel exception. On arm64, the result for LLONG_MIN/-1 is
LLONG_MIN.
Further investigation found all the following sdiv/smod cases may trigger
an exception when bpf program is running on x86_64 platform:
- LLONG_MIN/-1 for 64bit operation
- INT_MIN/-1 for 32bit operation
- LLONG_MIN%-1 for 64bit operation
- INT_MIN%-1 for 32bit operation
where -1 can be an immediate or in a register.
On arm64, there are no exceptions:
- LLONG_MIN/-1 = LLONG_MIN
- INT_MIN/-1 = INT_MIN
- LLONG_MIN%-1 = 0
- INT_MIN%-1 = 0
where -1 can be an immediate or in a register.
Insn patching is needed to handle the above cases and the patched codes
produced results aligned with above arm64 result. The below are pseudo
codes to handle sdiv/smod exceptions including both divisor -1 and divisor 0
and the divisor is stored in a register.
sdiv:
tmp = rX
tmp += 1 /* [-1, 0] -> [0, 1]
if tmp >(unsigned) 1 goto L2
if tmp == 0 goto L1
rY = 0
L1:
rY = -rY;
goto L3
L2:
rY /= rX
L3:
smod:
tmp = rX
tmp += 1 /* [-1, 0] -> [0, 1]
if tmp >(unsigned) 1 goto L1
if tmp == 1 (is64 ? goto L2 : goto L3)
rY = 0;
goto L2
L1:
rY %= rX
L2:
goto L4 // only when !is64
L3:
wY = wY // only when !is64
L4:
[1] https://lore.kernel.org/bpf/tPJLTEh7S_DxFEqAI2Ji5MBSoZVg7_G-Py2iaZpAaWtM961fFTWtsnlzwvTbzBzaUzwQAoNATXKUlt0LZOFgnDcIyKCswAnAGdUF3LBrhGQ=@protonmail.com/
Reported-by: Zac Ecob <zacecob@protonmail.com>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240913150326.1187788-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Pointers passed to tp_btf were trusted to be valid, but some tracepoints
do take NULL pointer as input, such as trace_tcp_send_reset(). Then the
invalid memory access cannot be detected by verifier.
This patch fix it by add a suffix "__nullable" to the unreliable
argument. The suffix is shown in btf, and PTR_MAYBE_NULL will be added
to nullable arguments. Then users must check the pointer before use it.
A problem here is that we use "btf_trace_##call" to search func_proto.
As it is a typedef, argument names as well as the suffix are not
recorded. To solve this, I use bpf_raw_event_map to find
"__bpf_trace##template" from "btf_trace_##call", and then we can see the
suffix.
Suggested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Philo Lu <lulie@linux.alibaba.com>
Link: https://lore.kernel.org/r/20240911033719.91468-2-lulie@linux.alibaba.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
When "arg#%d expected pointer to ctx, but got %s" error is printed, both
template parts actually point to the type of the argument, therefore, it
will also say "but got PTR", regardless of what was the actual register
type.
Fix the message to print the register type in the second part of the
template, change the existing test to adapt to the new format, and add a
new test to test the case when arg is a pointer to context, but reg is a
scalar.
Fixes: 00b85860fe ("bpf: Rewrite kfunc argument handling")
Signed-off-by: Maxim Mikityanskiy <maxim@isovalent.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/bpf/20240909133909.1315460-1-maxim@isovalent.com
Alexei Starovoitov
Cupertino Miranda
Puranjay Mohan
Eduard Zingerman
Paul Chaignon
Yonghong Song
Yazhou Tang
Leon Hwang
Jiri Olsa
Ihor Solodrai
Andrii Nakryiko
Amery Hung
Yafang Shao
Jiayuan Chen
Kumar Kartikeya Dwivedi
Andrea Righi
Tao Lyu
Jiri Olsa
Daniel Borkmann
Dimitar Kanaliev
Toke Høiland-Jørgensen
Rik van Riel
Linus Torvalds
Philo Lu
Maxim Mikityanskiy