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bpf: Consolidate sleepable checks in check_kfunc_call()

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check_kfunc_call() has multiple scattered checks that reject sleepable
kfuncs in various non-sleepable contexts (RCU, preempt-disabled, IRQ-
disabled). These are the same conditions already checked by
in_sleepable_context(), so replace them with a single consolidated
check.

This also simplifies the preempt lock tracking by flattening the nested
if/else structure into a linear chain: preempt_disable increments,
preempt_enable checks for underflow and decrements. The sleepable check
is kept as a separate block since it is logically distinct from the lock
accounting.

No functional change since in_sleepable_context() checks all the same
state (active_rcu_locks, active_preempt_locks, active_locks,
active_irq_id, in_sleepable).

Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Mykyta Yatsenko <yatsenko@meta.com>
Signed-off-by: Puranjay Mohan <puranjay@kernel.org>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20260318174327.3151925-3-puranjay@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Puranjay Mohan
2026-03-21 13:09:35 -07:00
committed by Alexei Starovoitov
parent a0d06cf102
commit cd9840c413
1 changed files with 13 additions and 23 deletions
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kernel/bpf/verifier.c
+13 -23
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@@ -14276,8 +14276,19 @@ static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
}
}));
}
} else if (sleepable && env->cur_state->active_rcu_locks) {
verbose(env, "kernel func %s is sleepable within rcu_read_lock region\n", func_name);
} else if (preempt_disable) {
env->cur_state->active_preempt_locks++;
} else if (preempt_enable) {
if (env->cur_state->active_preempt_locks == 0) {
verbose(env, "unmatched attempt to enable preemption (kernel function %s)\n", func_name);
return -EINVAL;
}
env->cur_state->active_preempt_locks--;
}
if (sleepable && !in_sleepable_context(env)) {
verbose(env, "kernel func %s is sleepable within %s\n",
func_name, non_sleepable_context_description(env));
return -EACCES;
}
@@ -14286,27 +14297,6 @@ static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
return -EACCES;
}
if (env->cur_state->active_preempt_locks) {
if (preempt_disable) {
env->cur_state->active_preempt_locks++;
} else if (preempt_enable) {
env->cur_state->active_preempt_locks--;
} else if (sleepable) {
verbose(env, "kernel func %s is sleepable within non-preemptible region\n", func_name);
return -EACCES;
}
} else if (preempt_disable) {
env->cur_state->active_preempt_locks++;
} else if (preempt_enable) {
verbose(env, "unmatched attempt to enable preemption (kernel function %s)\n", func_name);
return -EINVAL;
}
if (env->cur_state->active_irq_id && sleepable) {
verbose(env, "kernel func %s is sleepable within IRQ-disabled region\n", func_name);
return -EACCES;
}
if (is_kfunc_rcu_protected(&meta) && !in_rcu_cs(env)) {
verbose(env, "kernel func %s requires RCU critical section protection\n", func_name);
return -EACCES;