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=-18.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS 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 B880CC433B4 for ; Fri, 30 Apr 2021 18:10:07 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 5CD8E613BD for ; Fri, 30 Apr 2021 18:10:07 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5CD8E613BD Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=xmission.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id ED2798D0003; Fri, 30 Apr 2021 14:10:06 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id EAB896B0071; Fri, 30 Apr 2021 14:10:06 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D49FA8D0003; Fri, 30 Apr 2021 14:10:06 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0240.hostedemail.com [216.40.44.240]) by kanga.kvack.org (Postfix) with ESMTP id B5BC76B0070 for ; Fri, 30 Apr 2021 14:10:06 -0400 (EDT) Received: from smtpin32.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 7332C180ACF7F for ; Fri, 30 Apr 2021 18:10:06 +0000 (UTC) X-FDA: 78089822412.32.559F396 Received: from out01.mta.xmission.com (out01.mta.xmission.com [166.70.13.231]) by imf05.hostedemail.com (Postfix) with ESMTP id E7721E000131 for ; Fri, 30 Apr 2021 18:10:02 +0000 (UTC) Received: from in01.mta.xmission.com ([166.70.13.51]) by out01.mta.xmission.com with esmtps (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.93) (envelope-from ) id 1lcXaU-00CRau-5a; Fri, 30 Apr 2021 12:10:02 -0600 Received: from ip68-227-160-95.om.om.cox.net ([68.227.160.95] helo=fess.xmission.com) by in01.mta.xmission.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.87) (envelope-from ) id 1lcXaR-00085W-UW; Fri, 30 Apr 2021 12:10:01 -0600 From: ebiederm@xmission.com (Eric W. Biederman) To: Dan Carpenter Cc: kbuild@lists.01.org, legion@kernel.org, LKML , Kernel Hardening , Linux Containers , linux-mm@kvack.org, lkp@intel.com, kbuild-all@lists.01.org, Andrew Morton , Christian Brauner , Jann Horn References: <202104272256.9Y5ZQxrO-lkp@intel.com> Date: Fri, 30 Apr 2021 13:09:55 -0500 In-Reply-To: <202104272256.9Y5ZQxrO-lkp@intel.com> (Dan Carpenter's message of "Thu, 29 Apr 2021 17:04:23 +0300") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-XM-SPF: eid=1lcXaR-00085W-UW;;;mid=;;;hst=in01.mta.xmission.com;;;ip=68.227.160.95;;;frm=ebiederm@xmission.com;;;spf=neutral X-XM-AID: U2FsdGVkX18u6Xoo8s58CoWsQdxvXXEoS28W8e953RU= X-SA-Exim-Connect-IP: 68.227.160.95 X-SA-Exim-Mail-From: ebiederm@xmission.com Subject: [PATCH] ucounts: Silence warning in dec_rlimit_ucounts X-SA-Exim-Version: 4.2.1 (built Thu, 05 May 2016 13:38:54 -0600) X-SA-Exim-Scanned: Yes (on in01.mta.xmission.com) X-Stat-Signature: darmx8qsfd4k7bdpmxu7n5pi38nphiog X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: E7721E000131 Authentication-Results: imf05.hostedemail.com; dkim=none; spf=pass (imf05.hostedemail.com: domain of ebiederm@xmission.com designates 166.70.13.231 as permitted sender) smtp.mailfrom=ebiederm@xmission.com; dmarc=pass (policy=none) header.from=xmission.com Received-SPF: none (xmission.com>: No applicable sender policy available) receiver=imf05; identity=mailfrom; envelope-from=""; helo=out01.mta.xmission.com; client-ip=166.70.13.231 X-HE-DKIM-Result: none/none X-HE-Tag: 1619806202-183659 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: Dan Carpenter wrote: > > url: https://github.com/0day-ci/linux/commits/legion-kernel-org/Count-rlimits-in-each-user-namespace/20210427-162857 > base: https://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest.git next > config: arc-randconfig-m031-20210426 (attached as .config) > compiler: arceb-elf-gcc (GCC) 9.3.0 > > If you fix the issue, kindly add following tag as appropriate > Reported-by: kernel test robot > Reported-by: Dan Carpenter > > smatch warnings: > kernel/ucount.c:270 dec_rlimit_ucounts() error: uninitialized symbol 'new'. > > vim +/new +270 kernel/ucount.c > > 176ec2b092cc22 Alexey Gladkov 2021-04-22 260 bool dec_rlimit_ucounts(struct ucounts *ucounts, enum ucount_type type, long v) > 176ec2b092cc22 Alexey Gladkov 2021-04-22 261 { > 176ec2b092cc22 Alexey Gladkov 2021-04-22 262 struct ucounts *iter; > 176ec2b092cc22 Alexey Gladkov 2021-04-22 263 long new; > ^^^^^^^^ > > 176ec2b092cc22 Alexey Gladkov 2021-04-22 264 for (iter = ucounts; iter; iter = iter->ns->ucounts) { > 176ec2b092cc22 Alexey Gladkov 2021-04-22 265 long dec = atomic_long_add_return(-v, &iter->ucount[type]); > 176ec2b092cc22 Alexey Gladkov 2021-04-22 266 WARN_ON_ONCE(dec < 0); > 176ec2b092cc22 Alexey Gladkov 2021-04-22 267 if (iter == ucounts) > 176ec2b092cc22 Alexey Gladkov 2021-04-22 268 new = dec; > 176ec2b092cc22 Alexey Gladkov 2021-04-22 269 } > 176ec2b092cc22 Alexey Gladkov 2021-04-22 @270 return (new == 0); > ^^^^^^^^ > I don't know if this is a bug or not, but I can definitely tell why the > static checker complains about it. > > 176ec2b092cc22 Alexey Gladkov 2021-04-22 271 } In the only two cases that care about the return value of dec_rlimit_ucounts the code first tests to see that ucounts is not NULL. In those cases it is guaranteed at least one iteration of the loop will execute guaranteeing the variable new will be initialized. Initialize new to -1 so that the return value is well defined even when the loop does not execute and the static checker is silenced. Signed-off-by: "Eric W. Biederman" --- kernel/ucount.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/ucount.c b/kernel/ucount.c index d316bac3e520..12a48457bb86 100644 --- a/kernel/ucount.c +++ b/kernel/ucount.c @@ -263,7 +263,7 @@ long inc_rlimit_ucounts(struct ucounts *ucounts, enum ucount_type type, long v) bool dec_rlimit_ucounts(struct ucounts *ucounts, enum ucount_type type, long v) { struct ucounts *iter; - long new; + long new = -1; /* Silence compiler warnings */ for (iter = ucounts; iter; iter = iter->ns->ucounts) { long dec = atomic_long_add_return(-v, &iter->ucount[type]); WARN_ON_ONCE(dec < 0); -- 2.30.1