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 X-Spam-Level: X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_RED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6E4AAC433E6 for ; Sun, 24 Jan 2021 05:03:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 37386227BF for ; Sun, 24 Jan 2021 05:03:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726524AbhAXFDO (ORCPT ); Sun, 24 Jan 2021 00:03:14 -0500 Received: from mail.kernel.org ([198.145.29.99]:47612 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726192AbhAXFC7 (ORCPT ); Sun, 24 Jan 2021 00:02:59 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id A79B622CA1; Sun, 24 Jan 2021 05:02:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1611464539; bh=rV4ggstgXVVZo13vNCl7ATS5VQr6rVwe0P4vsUhQdCE=; h=Date:From:To:Subject:In-Reply-To:From; b=evCw1pelC9pR9w0W2moHdb/+3vfUmRfE1tkNd9r3MD92LOVfJ7X6bdGDUJ6OrxZc3 QTP2FLEbxvtJfSchA5fyj/37HKGUEc4gWIC47kMeIof8YM67rOl1TxIkwRnWM1D4bI TOCOOAhWJhg+s5bdFSt73sP+BMRMONrP4dGOAo5U= Date: Sat, 23 Jan 2021 21:02:16 -0800 From: Andrew Morton To: adobriyan@gmail.com, akpm@linux-foundation.org, hkallweit1@gmail.com, keescook@chromium.org, linux-mm@kvack.org, mcgrof@kernel.org, mhiramat@kernel.org, mhocko@suse.com, mm-commits@vger.kernel.org, nixiaoming@huawei.com, rdunlap@infradead.org, stable@vger.kernel.org, torvalds@linux-foundation.org, vbabka@suse.cz, yzaikin@google.com Subject: [patch 18/19] proc_sysctl: fix oops caused by incorrect command parameters Message-ID: <20210124050216.W3v89CyuW%akpm@linux-foundation.org> In-Reply-To: <20210123210029.a7c704d0cab204683e41ad10@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: Xiaoming Ni Subject: proc_sysctl: fix oops caused by incorrect command parameters The process_sysctl_arg() does not check whether val is empty before invoking strlen(val). If the command line parameter () is incorrectly configured and val is empty, oops is triggered. For example: "hung_task_panic=1" is incorrectly written as "hung_task_panic", oops is triggered. The call stack is as follows: Kernel command line: .... hung_task_panic ...... Call trace: __pi_strlen+0x10/0x98 parse_args+0x278/0x344 do_sysctl_args+0x8c/0xfc kernel_init+0x5c/0xf4 ret_from_fork+0x10/0x30 To fix it, check whether "val" is empty when "phram" is a sysctl field. Error codes are returned in the failure branch, and error logs are generated by parse_args(). Link: https://lkml.kernel.org/r/20210118133029.28580-1-nixiaoming@huawei.com Fixes: 3db978d480e2843 ("kernel/sysctl: support setting sysctl parameters from kernel command line") Signed-off-by: Xiaoming Ni Acked-by: Vlastimil Babka Cc: Luis Chamberlain Cc: Kees Cook Cc: Iurii Zaikin Cc: Alexey Dobriyan Cc: Michal Hocko Cc: Masami Hiramatsu Cc: Heiner Kallweit Cc: Randy Dunlap Cc: [5.8+] Signed-off-by: Andrew Morton --- fs/proc/proc_sysctl.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) --- a/fs/proc/proc_sysctl.c~proc_sysctl-fix-oops-caused-by-incorrect-command-parameters +++ a/fs/proc/proc_sysctl.c @@ -1770,6 +1770,12 @@ static int process_sysctl_arg(char *para return 0; } + if (!val) + return -EINVAL; + len = strlen(val); + if (len == 0) + return -EINVAL; + /* * To set sysctl options, we use a temporary mount of proc, look up the * respective sys/ file and write to it. To avoid mounting it when no @@ -1811,7 +1817,6 @@ static int process_sysctl_arg(char *para file, param, val); goto out; } - len = strlen(val); wret = kernel_write(file, val, len, &pos); if (wret < 0) { err = wret; _