mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2026-08-09 06:14:34 +02:00
Yonghong SongandAlexei Starovoitov
d1dbe443a0
arg_track_join() logs state transitions at CFG merge points. For
stack arg slots (r >= MAX_BPF_REG), it printed "r11:", "r12:", etc.,
which is misleading since r11 is a special register (BPF_REG_PARAMS)
not meaningful to the user.
Fix it to print "sa0:", "sa1:", etc., matching the per-instruction
transition log in arg_track_log() which already uses the "sa" prefix.
Update the existing stack_arg_pruning_type_mismatch selftest to expect
the corrected format.
Fixes: 2af4e79277 ("bpf: Extend liveness analysis to track stack argument slots")
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20260515225056.823086-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
448 lines
9.2 KiB
C
448 lines
9.2 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/* Copyright (c) 2026 Meta Platforms, Inc. and affiliates. */
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#include <linux/bpf.h>
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#include <bpf/bpf_helpers.h>
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#include "bpf_misc.h"
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struct {
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__uint(type, BPF_MAP_TYPE_HASH);
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__uint(max_entries, 1);
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__type(key, long long);
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__type(value, long long);
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} map_hash_8b SEC(".maps");
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#if (defined(__TARGET_ARCH_x86) || defined(__TARGET_ARCH_arm64)) && \
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defined(__BPF_FEATURE_STACK_ARGUMENT)
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__noinline __used
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static int subprog_6args(int a, int b, int c, int d, int e, int f)
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{
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return a + b + c + d + e + f;
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}
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__noinline __used
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static int subprog_7args(int a, int b, int c, int d, int e, int f, int g)
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{
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return a + b + c + d + e + f + g;
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}
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__noinline __used
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static long subprog_deref_arg6(long a, long b, long c, long d, long e, long *f)
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{
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return *f;
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}
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SEC("tc")
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__description("stack_arg: subprog with 6 args")
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__success __retval(21)
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__naked void stack_arg_6args(void)
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{
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asm volatile (
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"r1 = 1;"
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"r2 = 2;"
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"r3 = 3;"
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"r4 = 4;"
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"r5 = 5;"
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"*(u64 *)(r11 - 8) = 6;"
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"call subprog_6args;"
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"exit;"
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::: __clobber_all
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);
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}
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SEC("tc")
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__description("stack_arg: two subprogs with >5 args")
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__success __retval(90)
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__naked void stack_arg_two_subprogs(void)
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{
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asm volatile (
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"r1 = 1;"
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"r2 = 2;"
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"r3 = 3;"
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"r4 = 4;"
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"r5 = 5;"
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"*(u64 *)(r11 - 8) = 10;"
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"call subprog_6args;"
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"r6 = r0;"
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"r1 = 1;"
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"r2 = 2;"
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"r3 = 3;"
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"r4 = 4;"
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"r5 = 5;"
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"*(u64 *)(r11 - 16) = 30;"
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"*(u64 *)(r11 - 8) = 20;"
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"call subprog_7args;"
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"r0 += r6;"
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"exit;"
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::: __clobber_all
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);
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}
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SEC("tc")
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__description("stack_arg: read from uninitialized stack arg slot")
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__failure
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__msg("invalid read from stack arg off 8 depth 0")
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__naked void stack_arg_read_uninitialized(void)
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{
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asm volatile (
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"r0 = *(u64 *)(r11 + 8);"
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"r0 = 0;"
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"exit;"
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::: __clobber_all
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);
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}
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SEC("tc")
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__description("stack_arg: gap at offset -8, only wrote -16")
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__failure
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__msg("callee expects 7 args, stack arg1 is not initialized")
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__naked void stack_arg_gap_at_minus8(void)
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{
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asm volatile (
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"r1 = 1;"
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"r2 = 2;"
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"r3 = 3;"
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"r4 = 4;"
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"r5 = 5;"
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"*(u64 *)(r11 - 16) = 30;"
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"call subprog_7args;"
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"exit;"
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::: __clobber_all
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);
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}
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SEC("tc")
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__description("stack_arg: pruning with different stack arg types")
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__failure __log_level(2)
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__flag(BPF_F_TEST_STATE_FREQ)
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__msg("arg JOIN insn 9 -> 10 r1: fp0-8 + _ => fp0-8|fp0+0")
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__msg("arg JOIN insn 9 -> 10 sa0: fp0-8 + _ => fp0-8|fp0+0")
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__msg("R{{[0-9]}} invalid mem access 'scalar'")
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__naked void stack_arg_pruning_type_mismatch(void)
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{
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asm volatile (
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"call %[bpf_get_prandom_u32];"
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"r6 = r0;"
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/* local = 0 on program stack */
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"r7 = 0;"
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"*(u64 *)(r10 - 8) = r7;"
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/* Branch based on random value */
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"if r6 s> 3 goto l0_%=;"
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/* Path 1: store stack pointer to outgoing arg6 */
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"r1 = r10;"
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"r1 += -8;"
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"*(u64 *)(r11 - 8) = r1;"
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"goto l1_%=;"
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"l0_%=:"
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/* Path 2: store scalar to outgoing arg6 */
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"*(u64 *)(r11 - 8) = 42;"
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"l1_%=:"
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/* Call subprog that dereferences arg6 */
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"r1 = r6;"
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"r2 = 0;"
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"r3 = 0;"
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"r4 = 0;"
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"r5 = 0;"
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"call subprog_deref_arg6;"
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"exit;"
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:: __imm(bpf_get_prandom_u32)
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: __clobber_all
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);
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}
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SEC("tc")
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__description("stack_arg: release_reference invalidates stack arg slot")
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__failure
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__msg("callee expects 6 args, stack arg1 is not initialized")
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__naked void stack_arg_release_ref(void)
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{
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asm volatile (
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"r6 = r1;"
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/* struct bpf_sock_tuple tuple = {} */
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"r2 = 0;"
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"*(u32 *)(r10 - 8) = r2;"
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"*(u64 *)(r10 - 16) = r2;"
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"*(u64 *)(r10 - 24) = r2;"
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"*(u64 *)(r10 - 32) = r2;"
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"*(u64 *)(r10 - 40) = r2;"
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"*(u64 *)(r10 - 48) = r2;"
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/* sk = bpf_sk_lookup_tcp(ctx, &tuple, sizeof(tuple), 0, 0) */
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"r1 = r6;"
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"r2 = r10;"
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"r2 += -48;"
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"r3 = %[sizeof_bpf_sock_tuple];"
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"r4 = 0;"
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"r5 = 0;"
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"call %[bpf_sk_lookup_tcp];"
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/* r0 = sk (PTR_TO_SOCK_OR_NULL) */
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"if r0 == 0 goto l0_%=;"
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/* Store sock ref to outgoing arg6 slot */
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"*(u64 *)(r11 - 8) = r0;"
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/* Release the reference — invalidates the stack arg slot */
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"r1 = r0;"
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"call %[bpf_sk_release];"
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/* Call subprog that dereferences arg6 — should fail */
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"r1 = 1;"
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"r2 = 2;"
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"r3 = 3;"
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"r4 = 4;"
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"r5 = 5;"
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"call subprog_deref_arg6;"
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"l0_%=:"
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"r0 = 0;"
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"exit;"
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:
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: __imm(bpf_sk_lookup_tcp),
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__imm(bpf_sk_release),
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__imm_const(sizeof_bpf_sock_tuple, sizeof(struct bpf_sock_tuple))
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: __clobber_all
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);
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}
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SEC("tc")
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__description("stack_arg: pkt pointer in stack arg slot invalidated after pull_data")
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__failure
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__msg("callee expects 6 args, stack arg1 is not initialized")
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__naked void stack_arg_stale_pkt_ptr(void)
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{
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asm volatile (
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"r6 = r1;"
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"r7 = *(u32 *)(r6 + %[__sk_buff_data]);"
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"r8 = *(u32 *)(r6 + %[__sk_buff_data_end]);"
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/* check pkt has at least 1 byte */
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"r0 = r7;"
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"r0 += 8;"
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"if r0 > r8 goto l0_%=;"
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/* Store valid pkt pointer to outgoing arg6 slot */
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"*(u64 *)(r11 - 8) = r7;"
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/* bpf_skb_pull_data invalidates all pkt pointers */
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"r1 = r6;"
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"r2 = 0;"
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"call %[bpf_skb_pull_data];"
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/* Call subprog that dereferences arg6 — should fail */
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"r1 = 1;"
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"r2 = 2;"
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"r3 = 3;"
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"r4 = 4;"
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"r5 = 5;"
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"call subprog_deref_arg6;"
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"l0_%=:"
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"r0 = 0;"
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"exit;"
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:
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: __imm(bpf_skb_pull_data),
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__imm_const(__sk_buff_data, offsetof(struct __sk_buff, data)),
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__imm_const(__sk_buff_data_end, offsetof(struct __sk_buff, data_end))
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: __clobber_all
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);
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}
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SEC("tc")
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__description("stack_arg: null propagation rejects deref on null branch")
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__failure
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__msg("R{{[0-9]}} invalid mem access 'scalar'")
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__naked void stack_arg_null_propagation_fail(void)
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{
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asm volatile (
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"r1 = 0;"
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"*(u64 *)(r10 - 8) = r1;"
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/* r0 = bpf_map_lookup_elem(&map_hash_8b, &key) */
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"r2 = r10;"
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"r2 += -8;"
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"r1 = %[map_hash_8b] ll;"
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"call %[bpf_map_lookup_elem];"
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/* Store PTR_TO_MAP_VALUE_OR_NULL to outgoing arg6 slot */
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"*(u64 *)(r11 - 8) = r0;"
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/* null check on r0 */
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"if r0 != 0 goto l0_%=;"
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/*
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* On null branch, outgoing slot is SCALAR(0).
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* Call subprog that dereferences arg6 — should fail.
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*/
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"r1 = 0;"
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"r2 = 0;"
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"r3 = 0;"
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"r4 = 0;"
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"r5 = 0;"
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"call subprog_deref_arg6;"
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"l0_%=:"
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"r0 = 0;"
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"exit;"
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:
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: __imm(bpf_map_lookup_elem),
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__imm_addr(map_hash_8b)
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: __clobber_all
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);
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}
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SEC("tc")
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__description("stack_arg: missing store on one branch")
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__failure
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__msg("callee expects 7 args, stack arg1 is not initialized")
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__naked void stack_arg_missing_store_one_branch(void)
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{
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asm volatile (
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"call %[bpf_get_prandom_u32];"
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"r1 = 1;"
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"r2 = 2;"
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"r3 = 3;"
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"r4 = 4;"
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"r5 = 5;"
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/* Write arg7 (r11-16) before branch */
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"*(u64 *)(r11 - 16) = 20;"
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"if r0 > 0 goto l0_%=;"
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/* Path 1: write arg6 and call */
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"*(u64 *)(r11 - 8) = 10;"
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"r1 = 1;"
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"r2 = 2;"
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"r3 = 3;"
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"r4 = 4;"
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"r5 = 5;"
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"call subprog_7args;"
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"goto l1_%=;"
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"l0_%=:"
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/* Path 2: missing arg6 store, call should fail */
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"r1 = 1;"
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"r2 = 2;"
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"r3 = 3;"
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"r4 = 4;"
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"r5 = 5;"
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"call subprog_7args;"
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"l1_%=:"
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"r0 = 0;"
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"exit;"
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:: __imm(bpf_get_prandom_u32)
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: __clobber_all
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);
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}
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SEC("tc")
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__description("stack_arg: share a store for both branches")
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__success __retval(0)
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__naked void stack_arg_shared_store(void)
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{
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asm volatile (
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"call %[bpf_get_prandom_u32];"
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"r1 = 1;"
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"r2 = 2;"
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"r3 = 3;"
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"r4 = 4;"
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"r5 = 5;"
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/* Write arg7 (r11-16) before branch */
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"*(u64 *)(r11 - 16) = 20;"
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"if r0 > 0 goto l0_%=;"
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/* Path 1: write arg6 and call */
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"*(u64 *)(r11 - 8) = 10;"
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"r1 = 1;"
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"r2 = 2;"
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"r3 = 3;"
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"r4 = 4;"
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"r5 = 5;"
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"call subprog_7args;"
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"goto l1_%=;"
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"l0_%=:"
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/* Path 2: also write arg6 and call */
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"*(u64 *)(r11 - 8) = 30;"
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"r1 = 1;"
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"r2 = 2;"
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"r3 = 3;"
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"r4 = 4;"
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"r5 = 5;"
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"call subprog_7args;"
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"l1_%=:"
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"r0 = 0;"
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"exit;"
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:: __imm(bpf_get_prandom_u32)
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: __clobber_all
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);
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}
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SEC("tc")
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__description("stack_arg: write beyond max outgoing depth")
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__failure
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__msg("stack arg write offset -80 exceeds max 7 stack args")
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__naked void stack_arg_write_beyond_max(void)
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{
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asm volatile (
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"r1 = 1;"
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"r2 = 2;"
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"r3 = 3;"
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"r4 = 4;"
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"r5 = 5;"
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/* Write to offset -80, way beyond any callee's needs */
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"*(u64 *)(r11 - 80) = 99;"
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"*(u64 *)(r11 - 16) = 20;"
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"*(u64 *)(r11 - 8) = 10;"
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"call subprog_7args;"
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"r0 = 0;"
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"exit;"
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::: __clobber_all
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);
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}
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SEC("tc")
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__description("stack_arg: write unused stack arg slot")
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__failure
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__msg("func#0 writes 5 stack arg slots, but calls only require 2")
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__naked void stack_arg_write_unused_slot(void)
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{
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asm volatile (
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"r1 = 1;"
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"r2 = 2;"
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"r3 = 3;"
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"r4 = 4;"
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"r5 = 5;"
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/* Write to offset -40, unused for the callee */
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"*(u64 *)(r11 - 40) = 99;"
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"*(u64 *)(r11 - 16) = 20;"
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"*(u64 *)(r11 - 8) = 10;"
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"call subprog_7args;"
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"r0 = 0;"
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"exit;"
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::: __clobber_all
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);
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}
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SEC("tc")
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__description("stack_arg: sequential calls reuse slots")
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__failure
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__msg("callee expects 7 args, stack arg1 is not initialized")
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__naked void stack_arg_sequential_calls(void)
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{
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asm volatile (
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"r1 = 1;"
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"r2 = 2;"
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"r3 = 3;"
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"r4 = 4;"
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"r5 = 5;"
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"*(u64 *)(r11 - 8) = 6;"
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"*(u64 *)(r11 - 16) = 7;"
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"call subprog_7args;"
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"r6 = r0;"
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"r1 = 1;"
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"r2 = 2;"
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"r3 = 3;"
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"r4 = 4;"
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"r5 = 5;"
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"call subprog_7args;"
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"r0 += r6;"
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"exit;"
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::: __clobber_all
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);
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}
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#else
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SEC("socket")
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__description("stack_arg is not supported by compiler or jit, use a dummy test")
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__success
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int dummy_test(void)
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{
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return 0;
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}
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#endif
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char _license[] SEC("license") = "GPL";
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