From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:60844 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932804AbeB1P0k (ORCPT ); Wed, 28 Feb 2018 10:26:40 -0500 Subject: Patch "exec: avoid gcc-8 warning for get_task_comm" has been added to the 4.14-stable tree To: arnd@arndb.de, akpm@linux-foundation.org, alexander.levin@verizon.com, asarai@suse.de, ebiederm@xmission.com, frederic@kernel.org, gregkh@linuxfoundation.org, james.l.morris@oracle.com, keescook@chromium.org, mingo@kernel.org, peterz@infradead.org, serge@hallyn.com, tglx@linutronix.de, torvalds@linux-foundation.org, viro@zeniv.linux.org.uk Cc: , From: Date: Wed, 28 Feb 2018 16:25:52 +0100 Message-ID: <1519831552237198@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled exec: avoid gcc-8 warning for get_task_comm to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: exec-avoid-gcc-8-warning-for-get_task_comm.patch and it can be found in the queue-4.14 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From foo@baz Wed Feb 28 16:23:28 CET 2018 From: Arnd Bergmann Date: Thu, 14 Dec 2017 15:32:41 -0800 Subject: exec: avoid gcc-8 warning for get_task_comm From: Arnd Bergmann [ Upstream commit 3756f6401c302617c5e091081ca4d26ab604bec5 ] 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 callsites 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. Link: http://lkml.kernel.org/r/20171205151724.1764896-1-arnd@arndb.de Signed-off-by: Arnd Bergmann Suggested-by: Kees Cook Acked-by: Kees Cook Acked-by: Ingo Molnar Cc: Alexander Viro Cc: Peter Zijlstra Cc: Serge Hallyn Cc: James Morris Cc: Aleksa Sarai Cc: "Eric W. Biederman" Cc: Frederic Weisbecker Cc: Thomas Gleixner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- fs/exec.c | 7 +++---- include/linux/sched.h | 6 +++++- 2 files changed, 8 insertions(+), 5 deletions(-) --- a/fs/exec.c +++ b/fs/exec.c @@ -1216,15 +1216,14 @@ killed: return -EAGAIN; } -char *get_task_comm(char *buf, struct task_struct *tsk) +char *__get_task_comm(char *buf, size_t buf_size, struct task_struct *tsk) { - /* buf must be at least sizeof(tsk->comm) in size */ task_lock(tsk); - strncpy(buf, tsk->comm, sizeof(tsk->comm)); + strncpy(buf, tsk->comm, buf_size); task_unlock(tsk); return buf; } -EXPORT_SYMBOL_GPL(get_task_comm); +EXPORT_SYMBOL_GPL(__get_task_comm); /* * These functions flushes out all traces of the currently running executable --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1502,7 +1502,11 @@ static inline void set_task_comm(struct __set_task_comm(tsk, from, false); } -extern char *get_task_comm(char *to, struct task_struct *tsk); +extern char *__get_task_comm(char *to, size_t len, struct task_struct *tsk); +#define get_task_comm(buf, tsk) ({ \ + BUILD_BUG_ON(sizeof(buf) != TASK_COMM_LEN); \ + __get_task_comm(buf, sizeof(buf), tsk); \ +}) #ifdef CONFIG_SMP void scheduler_ipi(void); Patches currently in stable-queue which might be from arnd@arndb.de are queue-4.14/exec-avoid-gcc-8-warning-for-get_task_comm.patch queue-4.14/x86-asm-allow-again-using-asm.h-when-building-for-the-bpf-clang-target.patch queue-4.14/arm-dts-ls1021a-fix-incorrect-clock-references.patch