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=-8.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,UNPARSEABLE_RELAY, URIBL_BLOCKED,USER_AGENT_GIT 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 1947CC64EB8 for ; Thu, 4 Oct 2018 21:14:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C55EF20877 for ; Thu, 4 Oct 2018 21:14:51 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C55EF20877 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726278AbeJEEJ5 (ORCPT ); Fri, 5 Oct 2018 00:09:57 -0400 Received: from out30-130.freemail.mail.aliyun.com ([115.124.30.130]:42679 "EHLO out30-130.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725758AbeJEEJ5 (ORCPT ); Fri, 5 Oct 2018 00:09:57 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R931e4;CH=green;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04390;MF=yang.shi@linux.alibaba.com;NM=1;PH=DS;RN=10;SR=0;TI=SMTPD_---0T9zY.5M_1538687672; Received: from e19h19392.et15sqa.tbsite.net(mailfrom:yang.shi@linux.alibaba.com fp:SMTPD_---0T9zY.5M_1538687672) by smtp.aliyun-inc.com(127.0.0.1); Fri, 05 Oct 2018 05:14:40 +0800 From: Yang Shi To: vbabka@suse.cz, kirill.shutemov@linux.intel.com, mhocko@kernel.org, willy@infradead.org, ldufour@linux.vnet.ibm.com, colin.king@canonical.com, akpm@linux-foundation.org Cc: yang.shi@linux.alibaba.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH 1/2 -mm] mm: brk: fix unsigned compare against 0 issue Date: Fri, 5 Oct 2018 05:14:31 +0800 Message-Id: <1538687672-17795-1-git-send-email-yang.shi@linux.alibaba.com> X-Mailer: git-send-email 1.8.3.1 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Static analysis reported unsigned compare against 0 issue according to Colin Ian King. Defined an int temp variable to check the return value of __do_munmap(). Reported-by: Colin Ian King Cc: Vlastimil Babka Cc: Kirill A. Shutemov Cc: Michal Hocko Cc: Matthew Wilcox Cc: Laurent Dufour Cc: Andrew Morton Signed-off-by: Yang Shi --- Andrew, this should be able to be folded into the original patch. mm/mmap.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/mm/mmap.c b/mm/mmap.c index 68dc4fb..c78f7e9 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -242,17 +242,18 @@ static int do_brk_flags(unsigned long addr, unsigned long request, unsigned long * __do_munmap() may downgrade mmap_sem to read. */ if (brk <= mm->brk) { + int ret; /* * mm->brk need to be protected by write mmap_sem, update it * before downgrading mmap_sem. * When __do_munmap fail, it will be restored from origbrk. */ mm->brk = brk; - retval = __do_munmap(mm, newbrk, oldbrk-newbrk, &uf, true); - if (retval < 0) { + ret = __do_munmap(mm, newbrk, oldbrk-newbrk, &uf, true); + if (ret < 0) { mm->brk = origbrk; goto out; - } else if (retval == 1) + } else if (ret == 1) downgraded = true; goto success; } -- 1.8.3.1