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=-15.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 11543C433DB for ; Thu, 7 Jan 2021 06:15:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CDE3A22E00 for ; Thu, 7 Jan 2021 06:15:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726338AbhAGGPZ (ORCPT ); Thu, 7 Jan 2021 01:15:25 -0500 Received: from szxga05-in.huawei.com ([45.249.212.191]:10555 "EHLO szxga05-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725821AbhAGGPZ (ORCPT ); Thu, 7 Jan 2021 01:15:25 -0500 Received: from DGGEMS412-HUB.china.huawei.com (unknown [172.30.72.60]) by szxga05-in.huawei.com (SkyGuard) with ESMTP id 4DBGBV0kb3zMF8D; Thu, 7 Jan 2021 14:13:22 +0800 (CST) Received: from [10.67.102.197] (10.67.102.197) by DGGEMS412-HUB.china.huawei.com (10.3.19.212) with Microsoft SMTP Server id 14.3.498.0; Thu, 7 Jan 2021 14:14:25 +0800 Subject: Re: [PATCH] proc_sysclt: fix oops caused by incorrect command parameters. To: Kees Cook CC: , , , , , , , , References: <20201224074256.117413-1-nixiaoming@huawei.com> <202101061539.966EBB293@keescook> From: Xiaoming Ni Message-ID: <5ad6d160-3a4e-28bd-4e89-cb01a1815861@huawei.com> Date: Thu, 7 Jan 2021 14:14:18 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.0.1 MIME-Version: 1.0 In-Reply-To: <202101061539.966EBB293@keescook> Content-Type: text/plain; charset="gbk"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.67.102.197] X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/1/7 7:46, Kees Cook wrote: > subject typo: "sysclt" -> "sysctl" > > On Thu, Dec 24, 2020 at 03:42:56PM +0800, Xiaoming Ni wrote: >> 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". >> >> log: >> Kernel command line: .... hung_task_panic >> .... >> [000000000000000n] user address but active_mm is swapper >> Internal error: Oops: 96000005 [#1] SMP >> Modules linked in: >> CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.10.1 #1 >> Hardware name: linux,dummy-virt (DT) >> pstate: 40000005 (nZcv daif -PAN -UAO -TCO BTYPE=--) >> pc : __pi_strlen+0x10/0x98 >> lr : process_sysctl_arg+0x1e4/0x2ac >> sp : ffffffc01104bd40 >> x29: ffffffc01104bd40 x28: 0000000000000000 >> x27: ffffff80c0a4691e x26: ffffffc0102a7c8c >> x25: 0000000000000000 x24: ffffffc01104be80 >> x23: ffffff80c22f0b00 x22: ffffff80c02e28c0 >> x21: ffffffc0109f9000 x20: 0000000000000000 >> x19: ffffffc0107c08de x18: 0000000000000003 >> x17: ffffffc01105d000 x16: 0000000000000054 >> x15: ffffffffffffffff x14: 3030253078413830 >> x13: 000000000000ffff x12: 0000000000000000 >> x11: 0101010101010101 x10: 0000000000000005 >> x9 : 0000000000000003 x8 : ffffff80c0980c08 >> x7 : 0000000000000000 x6 : 0000000000000002 >> x5 : ffffff80c0235000 x4 : ffffff810f7c7ee0 >> x3 : 000000000000043a x2 : 00bdcc4ebacf1a54 >> x1 : 0000000000000000 x0 : 0000000000000000 >> Call trace: >> __pi_strlen+0x10/0x98 >> parse_args+0x278/0x344 >> do_sysctl_args+0x8c/0xfc >> kernel_init+0x5c/0xf4 >> ret_from_fork+0x10/0x30 >> Code: b200c3eb 927cec01 f2400c07 54000301 (a8c10c22) >> >> Fixes: 3db978d480e2843 ("kernel/sysctl: support setting sysctl parameters >> from kernel command line") >> Signed-off-by: Xiaoming Ni >> --- >> fs/proc/proc_sysctl.c | 3 +++ >> 1 file changed, 3 insertions(+) >> >> diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c >> index 317899222d7f..4516411a2b44 100644 >> --- a/fs/proc/proc_sysctl.c >> +++ b/fs/proc/proc_sysctl.c >> @@ -1757,6 +1757,9 @@ static int process_sysctl_arg(char *param, char *val, >> loff_t pos = 0; >> ssize_t wret; >> >> + if (!val) >> + return 0; >> + >> if (strncmp(param, "sysctl", sizeof("sysctl") - 1) == 0) { >> param += sizeof("sysctl") - 1; > > Otherwise, yeah, this is a good test to add. I would make it more > verbose, though: > > if (!val) { > pr_err("Missing param value! Expected '%s=...value...'\n", param); > return 0; > } > Yes, it's better to add log output. Thank you for your review. Do I need to send V2 patch based on review comments? Thanks Xiaoming Ni