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Date: Wed, 29 Jan 2025 23:15:03 +0000
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From: Quentin Monnet <qmo@kernel.org>
Subject: Re: [PATCH bpf-next] bpftool: Fix readlink usage in get_fd_type
To: Viktor Malik <vmalik@redhat.com>, bpf@vger.kernel.org
Cc: Alexei Starovoitov <ast@kernel.org>,
 Daniel Borkmann <daniel@iogearbox.net>, Andrii Nakryiko <andrii@kernel.org>,
 Martin KaFai Lau <martin.lau@linux.dev>, Eduard Zingerman
 <eddyz87@gmail.com>, Song Liu <song@kernel.org>,
 Yonghong Song <yonghong.song@linux.dev>,
 John Fastabend <john.fastabend@gmail.com>, KP Singh <kpsingh@kernel.org>,
 Stanislav Fomichev <sdf@fomichev.me>, Hao Luo <haoluo@google.com>,
 Jiri Olsa <jolsa@kernel.org>
References: <20250129071857.75182-1-vmalik@redhat.com>
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In-Reply-To: <20250129071857.75182-1-vmalik@redhat.com>
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2025-01-29 08:18 UTC+0100 ~ Viktor Malik <vmalik@redhat.com>
> The `readlink(path, buf, sizeof(buf))` call reads at most sizeof(buf)
> bytes and *does not* append null-terminator to buf. With respect to
> that, fix two pieces in get_fd_type:
> 
> 1. Change the truncation check to contain sizeof(buf) rather than
>    sizeof(path).
> 2. Append null-terminator to buf.
> 
> Reported by Coverity.
> 
> Signed-off-by: Viktor Malik <vmalik@redhat.com>

Nice, thank you!

Fixes: 71bb428fe2c1 ("tools: bpf: add bpftool")
Reviewed-by: Quentin Monnet <qmo@kernel.org>