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=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,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 7C03FC433F5 for ; Wed, 22 Sep 2021 15:34:53 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 0FA9460F4C for ; Wed, 22 Sep 2021 15:34:53 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 0FA9460F4C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 9C5F96B0075; Wed, 22 Sep 2021 11:34:52 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 973786B0078; Wed, 22 Sep 2021 11:34:52 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 86270940008; Wed, 22 Sep 2021 11:34:52 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0049.hostedemail.com [216.40.44.49]) by kanga.kvack.org (Postfix) with ESMTP id 6CA636B0075 for ; Wed, 22 Sep 2021 11:34:52 -0400 (EDT) Received: from smtpin03.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 276E127F4D for ; Wed, 22 Sep 2021 15:34:52 +0000 (UTC) X-FDA: 78615607224.03.936E7F2 Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) by imf10.hostedemail.com (Postfix) with ESMTP id 3A0766001981 for ; Wed, 22 Sep 2021 15:34:50 +0000 (UTC) X-IronPort-AV: E=McAfee;i="6200,9189,10115"; a="223665459" X-IronPort-AV: E=Sophos;i="5.85,314,1624345200"; d="scan'208";a="223665459" Received: from fmsmga006.fm.intel.com ([10.253.24.20]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Sep 2021 08:34:27 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.85,314,1624345200"; d="scan'208";a="702297959" Received: from shbuild999.sh.intel.com (HELO localhost) ([10.239.146.151]) by fmsmga006.fm.intel.com with ESMTP; 22 Sep 2021 08:34:26 -0700 Date: Wed, 22 Sep 2021 23:34:25 +0800 From: Feng Tang To: Chen Jun Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, mhocko@suse.com, rui.xiang@huawei.com Subject: Re: [PATCH v2 1/1] mm: Fix the uninitialized use in overcommit_policy_handler Message-ID: <20210922153425.GB68763@shbuild999.sh.intel.com> References: <20210922014122.47219-1-chenjun102@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210922014122.47219-1-chenjun102@huawei.com> User-Agent: Mutt/1.5.24 (2015-08-30) Authentication-Results: imf10.hostedemail.com; dkim=none; dmarc=fail reason="No valid SPF, No valid DKIM" header.from=intel.com (policy=none); spf=none (imf10.hostedemail.com: domain of feng.tang@intel.com has no SPF policy when checking 134.134.136.65) smtp.mailfrom=feng.tang@intel.com X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 3A0766001981 X-Stat-Signature: 7971ktgumtyo3obq5pfe74jtqb16crje X-HE-Tag: 1632324890-479311 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: Hi Jun, On Wed, Sep 22, 2021 at 01:41:22AM +0000, Chen Jun wrote: > An unexpected value of /proc/sys/vm/panic_on_oom we will get, > after running the following program. > > int main() > { > int fd = open("/proc/sys/vm/panic_on_oom", O_RDWR) should this be "/proc/sys/vm/overcommit_memory" > 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. Other than the nit above, it looks good to me, thanks! Reviewed-by: Feng Tang > Fixes: 56f3547bfa4d ("mm: adjust vm_committed_as_batch according to vm overcommit policy" > Signed-off-by: Chen Jun > --- > > v2: > * Check whether new_policy has been changed by proc_dointvec_minmax. > > mm/util.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/mm/util.c b/mm/util.c > index 4ddb6e186dd5..d5be67771850 100644 > --- a/mm/util.c > +++ b/mm/util.c > @@ -756,7 +756,7 @@ int overcommit_policy_handler(struct ctl_table *table, int write, void *buffer, > size_t *lenp, loff_t *ppos) > { > struct ctl_table t; > - int new_policy; > + int new_policy = -1; > int ret; > > /* > @@ -774,7 +774,7 @@ int overcommit_policy_handler(struct ctl_table *table, int write, void *buffer, > t = *table; > t.data = &new_policy; > ret = proc_dointvec_minmax(&t, write, buffer, lenp, ppos); > - if (ret) > + if (ret || new_policy == -1) > return ret; > > mm_compute_batch(new_policy); > -- > 2.17.1 >