linux-kernel - Re: [PATCH] selftests/bpf: fix signedness bug in redir

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Message-ID: <CAADnVQ+SSPhZNN05F2-MS_79Vhp+mSTWF3Ss1rcoWRnaDjFx+A@mail.gmail.com>
Date: Wed, 11 Jun 2025 12:51:21 -0700
From: Alexei Starovoitov <alexei.starovoitov@...il.com>
To: wangfushuai <wangfushuai@...du.com>
Cc: Andrii Nakryiko <andrii@...nel.org>, Eduard <eddyz87@...il.com>, 
	Mykola Lysenko <mykolal@...com>, Martin KaFai Lau <martin.lau@...ux.dev>, Song Liu <song@...nel.org>, 
	Yonghong Song <yonghong.song@...ux.dev>, John Fastabend <john.fastabend@...il.com>, 
	KP Singh <kpsingh@...nel.org>, Stanislav Fomichev <sdf@...ichev.me>, Hao Luo <haoluo@...gle.com>, 
	Jiri Olsa <jolsa@...nel.org>, Alexei Starovoitov <ast@...nel.org>, 
	Daniel Borkmann <daniel@...earbox.net>, Shuah Khan <shuah@...nel.org>, Michal Luczaj <mhal@...x.co>, 
	Jakub Sitnicki <jakub@...udflare.com>, Kui-Feng Lee <thinker.li@...il.com>, bpf <bpf@...r.kernel.org>, 
	"open list:KERNEL SELFTEST FRAMEWORK" <linux-kselftest@...r.kernel.org>, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] selftests/bpf: fix signedness bug in redir_partial()

On Sun, Jun 8, 2025 at 7:38 AM wangfushuai <wangfushuai@...du.com> wrote:
>
> When xsend() returns -1 (error), the check 'n < sizeof(buf)' incorrectly
> treats it as success due to unsigned promotion. Explicitly check for -1
> first.
>
> Fixes: a4b7193d8efd ("selftests/bpf: Add sockmap test for redirecting partial skb data")
> Signed-off-by: wangfushuai <wangfushuai@...du.com>

Looks good, but please spell out your name as First Last
in both From and Signed-off

Also use [PATCH bpf-next] in subject

pw-bot: cr

> ---
>  tools/testing/selftests/bpf/prog_tests/sockmap_listen.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/tools/testing/selftests/bpf/prog_tests/sockmap_listen.c b/tools/testing/selftests/bpf/prog_tests/sockmap_listen.c
> index 1d98eee7a2c3..f1bdccc7e4e7 100644
> --- a/tools/testing/selftests/bpf/prog_tests/sockmap_listen.c
> +++ b/tools/testing/selftests/bpf/prog_tests/sockmap_listen.c
> @@ -924,6 +924,8 @@ static void redir_partial(int family, int sotype, int sock_map, int parser_map)
>                 goto close;
>
>         n = xsend(c1, buf, sizeof(buf), 0);
> +       if (n == -1)
> +               goto close;
>         if (n < sizeof(buf))
>                 FAIL("incomplete write");
>
> --
> 2.36.1
>