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selftests/bpf: Add tests for bpf_throw lock leak from subprogs

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Add test cases to ensure the verifier correctly rejects bpf_throw from
subprogs when RCU, preempt, or IRQ locks are held:

  * reject_subprog_rcu_lock_throw: subprog acquires bpf_rcu_read_lock and
    then calls bpf_throw
  * reject_subprog_throw_preempt_lock: always-throwing subprog called while
    caller holds bpf_preempt_disable
  * reject_subprog_throw_irq_lock: always-throwing subprog called while
    caller holds bpf_local_irq_save

Assisted-by: Claude:claude-opus-4-6
Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20260320000809.643798-2-ihor.solodrai@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Ihor Solodrai
2026-03-19 17:08:09 -07:00
committed by Alexei Starovoitov
parent 6c2128505f
commit a1e5c46eae
1 changed files with 47 additions and 0 deletions
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47
tools/testing/selftests/bpf/progs/exceptions_fail.c
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@@ -9,6 +9,10 @@
extern void bpf_rcu_read_lock(void) __ksym;
extern void bpf_rcu_read_unlock(void) __ksym;
extern void bpf_preempt_disable(void) __ksym;
extern void bpf_preempt_enable(void) __ksym;
extern void bpf_local_irq_save(unsigned long *) __ksym;
extern void bpf_local_irq_restore(unsigned long *) __ksym;
#define private(name) SEC(".bss." #name) __hidden __attribute__((aligned(8)))
@@ -349,4 +353,47 @@ int reject_exception_throw_cb_diff(struct __sk_buff *ctx)
return 0;
}
__noinline static int always_throws(void)
{
bpf_throw(0);
return 0;
}
__noinline static int rcu_lock_then_throw(void)
{
bpf_rcu_read_lock();
bpf_throw(0);
return 0;
}
SEC("?tc")
__failure __msg("bpf_throw cannot be used inside bpf_rcu_read_lock-ed region")
int reject_subprog_rcu_lock_throw(void *ctx)
{
rcu_lock_then_throw();
return 0;
}
SEC("?tc")
__failure __msg("bpf_throw cannot be used inside bpf_preempt_disable-ed region")
int reject_subprog_throw_preempt_lock(void *ctx)
{
bpf_preempt_disable();
always_throws();
bpf_preempt_enable();
return 0;
}
SEC("?tc")
__failure __msg("bpf_throw cannot be used inside bpf_local_irq_save-ed region")
int reject_subprog_throw_irq_lock(void *ctx)
{
unsigned long flags;
bpf_local_irq_save(&flags);
always_throws();
bpf_local_irq_restore(&flags);
return 0;
}
char _license[] SEC("license") = "GPL";