diff options
| author | Florent Revest | 2021-04-23 01:55:42 +0200 |
|---|---|---|
| committer | Alexei Starovoitov | 2021-04-23 09:58:21 -0700 |
| commit | 8e8ee109b02c0e90021d63cd20dd0157c021f7a4 (patch) | |
| tree | 8abf8acf65295cbadcaeea0b76b1437f02c7e535 | |
| parent | e7a1c1300891d8f11d05b42665e299cc22a4b383 (diff) | |
bpf: Notify user if we ever hit a bpf_snprintf verifier bug
In check_bpf_snprintf_call(), a map_direct_value_addr() of the fmt map
should never fail because it has already been checked by
ARG_PTR_TO_CONST_STR. But if it ever fails, it's better to error out
with an explicit debug message rather than silently fail.
Reported-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Florent Revest <revest@chromium.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210422235543.4007694-2-revest@chromium.org
| -rw-r--r-- | kernel/bpf/verifier.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 58730872f7e5..59799a9b014a 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -5940,8 +5940,10 @@ static int check_bpf_snprintf_call(struct bpf_verifier_env *env, fmt_map_off = fmt_reg->off + fmt_reg->var_off.value; err = fmt_map->ops->map_direct_value_addr(fmt_map, &fmt_addr, fmt_map_off); - if (err) - return err; + if (err) { + verbose(env, "verifier bug\n"); + return -EFAULT; + } fmt = (char *)(long)fmt_addr + fmt_map_off; /* We are also guaranteed that fmt+fmt_map_off is NULL terminated, we |