From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 92AA1C433F5 for ; Wed, 13 Oct 2021 13:11:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 72E9861130 for ; Wed, 13 Oct 2021 13:11:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234875AbhJMNNO (ORCPT ); Wed, 13 Oct 2021 09:13:14 -0400 Received: from mail.kernel.org ([198.145.29.99]:60910 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235293AbhJMNNL (ORCPT ); Wed, 13 Oct 2021 09:13:11 -0400 Received: from gandalf.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id E26C561100; Wed, 13 Oct 2021 13:11:05 +0000 (UTC) Date: Wed, 13 Oct 2021 09:11:04 -0400 From: Steven Rostedt To: Yafang Shao Cc: keescook@chromium.org, peterz@infradead.org, pmladek@suse.com, viro@zeniv.linux.org.uk, akpm@linux-foundation.org, valentin.schneider@arm.com, mathieu.desnoyers@efficios.com, qiang.zhang@windriver.com, robdclark@chromium.org, christian@brauner.io, dietmar.eggemann@arm.com, mingo@redhat.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, bsegall@google.com, mgorman@suse.de, bristot@redhat.com, davem@davemloft.net, kuba@kernel.org, linux-kernel@vger.kernel.org, kernel test robot Subject: Re: [PATCH v4 1/5] elfcore: use TASK_COMM_LEN instead of 16 in prpsinfo Message-ID: <20211013091104.4ea0e05b@gandalf.local.home> In-Reply-To: <20211013102346.179642-2-laoar.shao@gmail.com> References: <20211013102346.179642-1-laoar.shao@gmail.com> <20211013102346.179642-2-laoar.shao@gmail.com> X-Mailer: Claws Mail 3.17.8 (GTK+ 2.24.33; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 13 Oct 2021 10:23:42 +0000 Yafang Shao wrote: > kernel test robot reported a -Wstringop-truncation warning after I > extend task comm from 16 to 24. Below is the detailed warning: > > fs/binfmt_elf.c: In function 'fill_psinfo.isra': > >> fs/binfmt_elf.c:1575:9: warning: 'strncpy' output may be truncated copying 16 bytes from a string of length 23 [-Wstringop-truncation] > 1575 | strncpy(psinfo->pr_fname, p->comm, sizeof(psinfo->pr_fname)); > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > This patch can fix this warning. > > struct elf_prpsinfo was moved from include/uapi/linux/elfcore.h into > include/linux/elfcore.h in commit > 1e6b57d6421f ("unexport linux/elfcore.h") > > As it is not UAPI code, we can replace 16 with TASK_COMM_LEN without > worrying about breaking userspace things. > > struct elf_prpsinfo is used to dump the task information in userspace > coredump or kernel vmcore. So I verified what will happen to vmcore if > I extend the size of TASK_COMM_LEN to 24. The result is that the vmcore > still work fine as expected, for example: > > crash> ps > PID PPID CPU TASK ST %MEM VSZ RSS COMM > > 0 0 0 ffffffff8501a940 RU 0.0 0 0 [swapper/0] > > 0 0 1 ffff996e00f81f80 RU 0.0 0 0 [swapper/1] > > 0 0 2 ffff996e00f80000 RU 0.0 0 0 [swapper/2] > > 0 0 3 ffff996e00f85e80 RU 0.0 0 0 [swapper/3] > > 0 0 4 ffff996e00f83f00 RU 0.0 0 0 [swapper/4] > 0 0 5 ffff996e00f8de80 RU 0.0 0 0 [swapper/5] > > 0 0 6 ffff996e00f8bf00 RU 0.0 0 0 [swapper/6] > > 0 0 7 ffff996e00f89f80 RU 0.0 0 0 [swapper/7] > > 0 0 8 ffff996e00f88000 RU 0.0 0 0 [swapper/8] > > 0 0 9 ffff996e00f93f00 RU 0.0 0 0 [swapper/9] > > 0 0 10 ffff996e00f91f80 RU 0.0 0 0 [swapper/10] > > 0 0 11 ffff996e00f90000 RU 0.0 0 0 [swapper/11] > > 0 0 12 ffff996e00f95e80 RU 0.0 0 0 [swapper/12] > > 0 0 13 ffff996e00f98000 RU 0.0 0 0 [swapper/13] > > 0 0 14 ffff996e00f9de80 RU 0.0 0 0 [swapper/14] > > 0 0 15 ffff996e00f9bf00 RU 0.0 0 0 [swapper/15] > > Reported-by: kernel test robot > Signed-off-by: Yafang Shao > Cc: Peter Zijlstra > Cc: Steven Rostedt > Cc: Kees Cook > Cc: Al Viro > Cc: Petr Mladek > --- > include/linux/elfcore-compat.h | 2 +- > include/linux/elfcore.h | 4 ++-- > 2 files changed, 3 insertions(+), 3 deletions(-) > > diff --git a/include/linux/elfcore-compat.h b/include/linux/elfcore-compat.h > index e272c3d452ce..8a52a782161d 100644 > --- a/include/linux/elfcore-compat.h > +++ b/include/linux/elfcore-compat.h > @@ -43,7 +43,7 @@ struct compat_elf_prpsinfo > __compat_uid_t pr_uid; > __compat_gid_t pr_gid; > compat_pid_t pr_pid, pr_ppid, pr_pgrp, pr_sid; > - char pr_fname[16]; > + char pr_fname[TASK_COMM_LEN]; > char pr_psargs[ELF_PRARGSZ]; > }; Nice clean up, but should we add "#include " to this header, to make sure that it pulls in TASK_COMM_LEN define and not just hope it gets pulled in beforehand by chance? > > diff --git a/include/linux/elfcore.h b/include/linux/elfcore.h > index 2aaa15779d50..ff4e4e455160 100644 > --- a/include/linux/elfcore.h > +++ b/include/linux/elfcore.h > @@ -65,8 +65,8 @@ struct elf_prpsinfo > __kernel_gid_t pr_gid; > pid_t pr_pid, pr_ppid, pr_pgrp, pr_sid; > /* Lots missing */ > - char pr_fname[16]; /* filename of executable */ > - char pr_psargs[ELF_PRARGSZ]; /* initial part of arg list */ > + char pr_fname[TASK_COMM_LEN]; /* filename of executable */ > + char pr_psargs[ELF_PRARGSZ]; /* initial part of arg list */ This header is fine, as it pulls in sched/task_stack.h which includes sched.h. -- Steve > }; > > static inline void elf_core_copy_regs(elf_gregset_t *elfregs, struct pt_regs *regs)