From: Daniel Borkmann <daniel@iogearbox.net>
To: Matteo Croce <mcroce@redhat.com>,
xdp-newbies@vger.kernel.org, bpf@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
Alexei Starovoitov <ast@kernel.org>
Subject: Re: [PATCH bpf] samples/bpf: suppress compiler warning
Date: Tue, 21 May 2019 16:56:34 +0200 [thread overview]
Message-ID: <f874efcb-f2a2-1d5f-7c43-cebdb828e465@iogearbox.net> (raw)
In-Reply-To: <20190520214938.16889-1-mcroce@redhat.com>
On 05/20/2019 11:49 PM, Matteo Croce wrote:
> GCC 9 fails to calculate the size of local constant strings and produces a
> false positive:
>
> samples/bpf/task_fd_query_user.c: In function ‘test_debug_fs_uprobe’:
> samples/bpf/task_fd_query_user.c:242:67: warning: ‘%s’ directive output may be truncated writing up to 255 bytes into a region of size 215 [-Wformat-truncation=]
> 242 | snprintf(buf, sizeof(buf), "/sys/kernel/debug/tracing/events/%ss/%s/id",
> | ^~
> 243 | event_type, event_alias);
> | ~~~~~~~~~~~
> samples/bpf/task_fd_query_user.c:242:2: note: ‘snprintf’ output between 45 and 300 bytes into a destination of size 256
> 242 | snprintf(buf, sizeof(buf), "/sys/kernel/debug/tracing/events/%ss/%s/id",
> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 243 | event_type, event_alias);
> | ~~~~~~~~~~~~~~~~~~~~~~~~
>
> Workaround this by lowering the buffer size to a reasonable value.
> Related GCC Bugzilla: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83431
>
> Signed-off-by: Matteo Croce <mcroce@redhat.com>
Applied, thanks!
prev parent reply other threads:[~2019-05-21 14:56 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-20 21:49 [PATCH bpf] samples/bpf: suppress compiler warning Matteo Croce
2019-05-21 14:56 ` Daniel Borkmann [this message]
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