From: Kees Cook <keescook@chromium.org>
To: Ingo Molnar <mingo@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Serge Hallyn <serge@hallyn.com>,
James Morris <james.l.morris@oracle.com>,
Andrew Morton <akpm@linux-foundation.org>,
Aleksa Sarai <asarai@suse.de>,
"Eric W. Biederman" <ebiederm@xmission.com>,
Frederic Weisbecker <frederic@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2] exec: avoid gcc-8 warning for get_task_comm
Date: Wed, 6 Dec 2017 15:09:20 -0800 [thread overview]
Message-ID: <CAGXu5jLdKk+WBhPLfZoQbbXqh7nsRftu-nJrvDs7KLdcs6knxg@mail.gmail.com> (raw)
In-Reply-To: <20171206174934.e5s6c5dh5lscwkyp@gmail.com>
On Wed, Dec 6, 2017 at 9:49 AM, Ingo Molnar <mingo@kernel.org> wrote:
>
> * Arnd Bergmann <arnd@arndb.de> wrote:
>
>> gcc-8 warns about using strncpy() with the source size as the limit:
>>
>> fs/exec.c:1223:32: error: argument to 'sizeof' in 'strncpy' call is the same expression as the source; did you mean to use the size of the destination? [-Werror=sizeof-pointer-memaccess]
>>
>> This is indeed slightly suspicious, as it protects us from source
>> arguments without NUL-termination, but does not guarantee that the
>> destination is terminated.
>>
>> This keeps the strncpy() to ensure we have properly padded target buffer,
>> but ensures that we use the correct length, by passing the actual length
>> of the destination buffer as well as adding a build-time check to ensure
>> it is exactly TASK_COMM_LEN. There are only 23 callsights which I all
>> reviewed to ensure this is currently the case. We could get away with
>> doing only the check or passing the right length, but it doesn't hurt
>> to do both.
>>
>> Suggested-by: Kees Cook <keescook@chromium.org>
>> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
>
> Looks useful.
>
> Acked-by: Ingo Molnar <mingo@kernel.org>
Ingo, can you take this into -tip, or should this go via -mm or some other tree?
-Kees
--
Kees Cook
Pixel Security
next prev parent reply other threads:[~2017-12-06 23:09 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-05 15:17 [PATCH v2] exec: avoid gcc-8 warning for get_task_comm Arnd Bergmann
2017-12-05 19:09 ` Kees Cook
2017-12-06 10:11 ` David Laight
2017-12-06 17:49 ` Ingo Molnar
2017-12-06 23:09 ` Kees Cook [this message]
2017-12-06 23:29 ` Andrew Morton
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