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=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 86423C433EF for ; Wed, 22 Sep 2021 15:37:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6447161278 for ; Wed, 22 Sep 2021 15:37:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236457AbhIVPjB (ORCPT ); Wed, 22 Sep 2021 11:39:01 -0400 Received: from mga06.intel.com ([134.134.136.31]:1118 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236400AbhIVPjA (ORCPT ); Wed, 22 Sep 2021 11:39:00 -0400 X-IronPort-AV: E=McAfee;i="6200,9189,10115"; a="284634130" X-IronPort-AV: E=Sophos;i="5.85,314,1624345200"; d="scan'208";a="284634130" Received: from fmsmga006.fm.intel.com ([10.253.24.20]) by orsmga104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Sep 2021 08:34:28 -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) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 >