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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS autolearn=no 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 98089C433FE for ; Fri, 24 Sep 2021 02:23:15 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 17A75610F7 for ; Fri, 24 Sep 2021 02:23:15 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 17A75610F7 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 99E416B006C; Thu, 23 Sep 2021 22:23:14 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 94D4F6B0071; Thu, 23 Sep 2021 22:23:14 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 863446B0073; Thu, 23 Sep 2021 22:23:14 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0019.hostedemail.com [216.40.44.19]) by kanga.kvack.org (Postfix) with ESMTP id 76AA86B006C for ; Thu, 23 Sep 2021 22:23:14 -0400 (EDT) Received: from smtpin14.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 1CFCD8249980 for ; Fri, 24 Sep 2021 02:23:14 +0000 (UTC) X-FDA: 78620869908.14.B9C9F7E Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf05.hostedemail.com (Postfix) with ESMTP id B6C5B50645B1 for ; Fri, 24 Sep 2021 02:23:13 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id A33B26103D; Fri, 24 Sep 2021 02:23:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1632450192; bh=ctCfw8qHq/1/s2IJwPV0nP8KA/ZQAL0nkypcKWxNDPw=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=FTPBfEd4jaMCiY2JfK5xgsf6d7mKAiIuNZVVFHP90JdFtrFt1QREhmFXntTzLbmun ME3VSaJG+IsZ1+NqRMz/MUnNVeOuagRUydHNvr4IVmwoEcCmFJ9b4J2HiUDsTYYWeN zCeLNKJ+pk5ziE7b4/z1iYbuTNSb29sRjZmFFdRo= Date: Thu, 23 Sep 2021 19:23:12 -0700 From: Andrew Morton To: Chen Jun Cc: , , , , Subject: Re: [PATCH v3 1/1] mm: Fix the uninitialized use in overcommit_policy_handler Message-Id: <20210923192312.53dbe65db0375038c99defaa@linux-foundation.org> In-Reply-To: <20210923020524.13289-1-chenjun102@huawei.com> References: <20210923020524.13289-1-chenjun102@huawei.com> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: B6C5B50645B1 X-Stat-Signature: uda85ysg9p1obf9y3nedzj7c8ypzg84m Authentication-Results: imf05.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=FTPBfEd4; dmarc=none; spf=pass (imf05.hostedemail.com: domain of akpm@linux-foundation.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org X-HE-Tag: 1632450193-215911 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, 23 Sep 2021 02:05:24 +0000 Chen Jun wrote: > An unexpected value of /proc/sys/vm/overcommit_memory we will get, > after running the following program. > > int main() > { > int fd = open("/proc/sys/vm/overcommit_memory", O_RDWR) > write(fd, "1", 1); > write(fd, "2", 1); > close(fd); > } > > write(fd, "2", 1) will pass *ppos = 1 to proc_dointvec_minmax. > proc_dointvec_minmax will return 0 without setting new_policy. > > t.data = &new_policy; > ret = proc_dointvec_minmax(&t, write, buffer, lenp, ppos) > -->do_proc_dointvec > -->__do_proc_dointvec > if (write) { > if (proc_first_pos_non_zero_ignore(ppos, table)) > goto out; > > sysctl_overcommit_memory = new_policy; > > so sysctl_overcommit_memory will be set to an uninitialized value. > > Check whether new_policy has been changed by proc_dointvec_minmax. > Thanks. I added a cc:stable to this, so the fix will be backported into earlier kernels.