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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 12D47C433FE for ; Thu, 20 Jan 2022 02:08:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1358179AbiATCIk (ORCPT ); Wed, 19 Jan 2022 21:08:40 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34326 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1358174AbiATCIi (ORCPT ); Wed, 19 Jan 2022 21:08:38 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F1EC4C061574 for ; Wed, 19 Jan 2022 18:08:31 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 914EA61522 for ; Thu, 20 Jan 2022 02:08:31 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 632FCC340E4; Thu, 20 Jan 2022 02:08:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1642644511; bh=tuA00zobsKV9+rwRge9Ef+/v2Iw7dSKpX0IpOuUrM3s=; h=Date:From:To:Subject:In-Reply-To:From; b=G3F24mX9FMTXhk0ISq67Lm7Ghh+AnsFYkWdstCuEqvhIrisAVA5w56NLMuumdOcyX 0QGA9Yr4gDL0gBn4KWdJRY5DcBnztHGkXe32/mqhgNvS++1Q6m/pZH6f/FxmZBayKV K+UOIcBJHZnFOVJe4l3NsV9yQHDANvbphsw1X2tY= Date: Wed, 19 Jan 2022 18:08:29 -0800 From: Andrew Morton To: akpm@linux-foundation.org, alexei.starovoitov@gmail.com, andrii.nakryiko@gmail.com, andrii@kernel.org, arnaldo.melo@gmail.com, david@redhat.com, dennis.dalessandro@cornelisnetworks.com, keescook@chromium.org, laoar.shao@gmail.com, linux-mm@kvack.org, mathieu.desnoyers@efficios.com, mirq-linux@rere.qmqm.pl, mm-commits@vger.kernel.org, peterz@infradead.org, pmladek@suse.com, rostedt@goodmis.org, torvalds@linux-foundation.org, viro@zeniv.linux.org.uk, willy@infradead.org Subject: [patch 15/55] fs/binfmt_elf: replace open-coded string copy with get_task_comm Message-ID: <20220120020829.JQpgP8Lo0%akpm@linux-foundation.org> In-Reply-To: <20220119180714.9e187ce100e4510de3cd9f7d@linux-foundation.org> User-Agent: s-nail v14.8.16 Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org From: Yafang Shao Subject: fs/binfmt_elf: replace open-coded string copy with get_task_comm It is better to use get_task_comm() instead of the open coded string copy as we do in other places. struct elf_prpsinfo is used to dump the task information in userspace coredump or kernel vmcore. Below is the verification of vmcore, crash> ps PID PPID CPU TASK ST %MEM VSZ RSS COMM 0 0 0 ffffffff9d21a940 RU 0.0 0 0 [swapper/0] > 0 0 1 ffffa09e40f85e80 RU 0.0 0 0 [swapper/1] > 0 0 2 ffffa09e40f81f80 RU 0.0 0 0 [swapper/2] > 0 0 3 ffffa09e40f83f00 RU 0.0 0 0 [swapper/3] > 0 0 4 ffffa09e40f80000 RU 0.0 0 0 [swapper/4] > 0 0 5 ffffa09e40f89f80 RU 0.0 0 0 [swapper/5] 0 0 6 ffffa09e40f8bf00 RU 0.0 0 0 [swapper/6] > 0 0 7 ffffa09e40f88000 RU 0.0 0 0 [swapper/7] > 0 0 8 ffffa09e40f8de80 RU 0.0 0 0 [swapper/8] > 0 0 9 ffffa09e40f95e80 RU 0.0 0 0 [swapper/9] > 0 0 10 ffffa09e40f91f80 RU 0.0 0 0 [swapper/10] > 0 0 11 ffffa09e40f93f00 RU 0.0 0 0 [swapper/11] > 0 0 12 ffffa09e40f90000 RU 0.0 0 0 [swapper/12] > 0 0 13 ffffa09e40f9bf00 RU 0.0 0 0 [swapper/13] > 0 0 14 ffffa09e40f98000 RU 0.0 0 0 [swapper/14] > 0 0 15 ffffa09e40f9de80 RU 0.0 0 0 [swapper/15] It works well as expected. Some comments are added to explain why we use the hard-coded 16. Link: https://lkml.kernel.org/r/20211120112738.45980-5-laoar.shao@gmail.com Suggested-by: Kees Cook Signed-off-by: Yafang Shao Reviewed-by: David Hildenbrand Cc: Mathieu Desnoyers Cc: Arnaldo Carvalho de Melo Cc: Andrii Nakryiko Cc: Michal Miroslaw Cc: Peter Zijlstra Cc: Steven Rostedt Cc: Matthew Wilcox Cc: David Hildenbrand Cc: Al Viro Cc: Kees Cook Cc: Petr Mladek Cc: Alexei Starovoitov Cc: Andrii Nakryiko Cc: Dennis Dalessandro Signed-off-by: Andrew Morton --- fs/binfmt_elf.c | 2 +- include/linux/elfcore-compat.h | 5 +++++ include/linux/elfcore.h | 5 +++++ 3 files changed, 11 insertions(+), 1 deletion(-) --- a/fs/binfmt_elf.c~fs-binfmt_elf-replace-open-coded-string-copy-with-get_task_comm +++ a/fs/binfmt_elf.c @@ -1585,7 +1585,7 @@ static int fill_psinfo(struct elf_prpsin SET_UID(psinfo->pr_uid, from_kuid_munged(cred->user_ns, cred->uid)); SET_GID(psinfo->pr_gid, from_kgid_munged(cred->user_ns, cred->gid)); rcu_read_unlock(); - strncpy(psinfo->pr_fname, p->comm, sizeof(psinfo->pr_fname)); + get_task_comm(psinfo->pr_fname, p); return 0; } --- a/include/linux/elfcore-compat.h~fs-binfmt_elf-replace-open-coded-string-copy-with-get_task_comm +++ a/include/linux/elfcore-compat.h @@ -43,6 +43,11 @@ 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; + /* + * The hard-coded 16 is derived from TASK_COMM_LEN, but it can't be + * changed as it is exposed to userspace. We'd better make it hard-coded + * here. + */ char pr_fname[16]; char pr_psargs[ELF_PRARGSZ]; }; --- a/include/linux/elfcore.h~fs-binfmt_elf-replace-open-coded-string-copy-with-get_task_comm +++ a/include/linux/elfcore.h @@ -65,6 +65,11 @@ struct elf_prpsinfo __kernel_gid_t pr_gid; pid_t pr_pid, pr_ppid, pr_pgrp, pr_sid; /* Lots missing */ + /* + * The hard-coded 16 is derived from TASK_COMM_LEN, but it can't be + * changed as it is exposed to userspace. We'd better make it hard-coded + * here. + */ char pr_fname[16]; /* filename of executable */ char pr_psargs[ELF_PRARGSZ]; /* initial part of arg list */ }; _