[PATCH] bpf: Fix a erroneous check after snprintf()

[PATCH] bpf: Fix a erroneous check after snprintf()

[Christophe JAILLET]

snprintf() does not return negative error code on error, it returns the
number of characters which *would* be generated for the given input.

Fix the error handling check.

Fixes: 57539b1c0ac2 ("bpf: Enable annotating trusted nested pointers")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
---
 kernel/bpf/btf.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 1095bbe29859..8090d7fb11ef 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -8501,7 +8501,7 @@ bool btf_nested_type_is_trusted(struct bpf_verifier_log *log,
 	tname = btf_name_by_offset(btf, walk_type->name_off);
 
 	ret = snprintf(safe_tname, sizeof(safe_tname), "%s%s", tname, suffix);
-	if (ret < 0)
+	if (ret >= sizeof(safe_tname))
 		return false;
 
 	safe_id = btf_find_by_name_kind(btf, safe_tname, BTF_INFO_KIND(walk_type->info));
-- 
2.34.1

Re: [PATCH] bpf: Fix a erroneous check after snprintf()

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to bpf/bpf.git (master)
by Alexei Starovoitov <ast@kernel.org>:

On Fri,  8 Sep 2023 18:33:35 +0200 you wrote:
> snprintf() does not return negative error code on error, it returns the
> number of characters which *would* be generated for the given input.
> 
> Fix the error handling check.
> 
> Fixes: 57539b1c0ac2 ("bpf: Enable annotating trusted nested pointers")
> Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
> 
> [...]

Here is the summary with links:
  - bpf: Fix a erroneous check after snprintf()
    https://git.kernel.org/bpf/bpf/c/a8f12572860a

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html