diff options
| author | Jiri Olsa <olsajiri@gmail.com> | 2025-08-14 22:06:55 +0200 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2025-08-15 11:16:56 +0200 |
| commit | e4414b01c1cd9887bbde92f946c1ba94e40d6d64 (patch) | |
| tree | f4104f957b7f624f7cb4f2f18b364a3a57283890 | |
| parent | 2b986b9e917bc88f81aa1ed386af63b26c983f1d (diff) | |
bpf: Check the helper function is valid in get_helper_proto
kernel test robot reported verifier bug [1] where the helper func
pointer could be NULL due to disabled config option.
As Alexei suggested we could check on that in get_helper_proto
directly. Marking tail_call helper func with BPF_PTR_POISON,
because it is unused by design.
[1] https://lore.kernel.org/oe-lkp/202507160818.68358831-lkp@intel.com
Reported-by: kernel test robot <oliver.sang@intel.com>
Reported-by: syzbot+a9ed3d9132939852d0df@syzkaller.appspotmail.com
Suggested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Paul Chaignon <paul.chaignon@gmail.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20250814200655.945632-1-jolsa@kernel.org
Closes: https://lore.kernel.org/oe-lkp/202507160818.68358831-lkp@intel.com
| -rw-r--r-- | kernel/bpf/core.c | 5 | ||||
| -rw-r--r-- | kernel/bpf/verifier.c | 2 |
2 files changed, 5 insertions, 2 deletions
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 5d1650af899d..f8ac77d08ca7 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -3024,7 +3024,10 @@ EXPORT_SYMBOL_GPL(bpf_event_output); /* Always built-in helper functions. */ const struct bpf_func_proto bpf_tail_call_proto = { - .func = NULL, + /* func is unused for tail_call, we set it to pass the + * get_helper_proto check + */ + .func = BPF_PTR_POISON, .gpl_only = false, .ret_type = RET_VOID, .arg1_type = ARG_PTR_TO_CTX, diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index c4f69a9e9af6..c89e2b1bc644 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -11354,7 +11354,7 @@ static int get_helper_proto(struct bpf_verifier_env *env, int func_id, return -EINVAL; *ptr = env->ops->get_func_proto(func_id, env->prog); - return *ptr ? 0 : -EINVAL; + return *ptr && (*ptr)->func ? 0 : -EINVAL; } static int check_helper_call(struct bpf_verifier_env *env, struct bpf_insn *insn, |