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bpf: Add __rcu_read_{lock,unlock} into btf id deny list

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The tracing recursion prevention mechanism must be protected by rcu, that
leaves __rcu_read_{lock,unlock} unprotected by this mechanism. If we trace
them, the recursion will happen. Let's add them into the btf id deny list.

When CONFIG_PREEMPT_RCU is enabled, it can be reproduced with a simple bpf
program as such:
  SEC("fentry/__rcu_read_lock")
  int fentry_run()
  {
      return 0;
  }

Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Link: https://lore.kernel.org/r/20230424161104.3737-2-laoar.shao@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Yafang Shao 2023-04-24 16:11:03 +00:00 committed by Alexei Starovoitov
parent 7deca5eae8
commit a0c109dcaf
1 changed files with 4 additions and 0 deletions
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4
kernel/bpf/verifier.c
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@ -18671,6 +18671,10 @@ BTF_ID(func, rcu_read_unlock_strict)
BTF_ID(func, preempt_count_add)
BTF_ID(func, preempt_count_sub)
#endif
#ifdef CONFIG_PREEMPT_RCU
BTF_ID(func, __rcu_read_lock)
BTF_ID(func, __rcu_read_unlock)
#endif
BTF_SET_END(btf_id_deny)
static bool can_be_sleepable(struct bpf_prog *prog)