From patchwork Tue Apr 7 09:51:07 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Miles Chen X-Patchwork-Id: 11477833 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id EE9F692A for ; Tue, 7 Apr 2020 09:51:22 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id B254620719 for ; Tue, 7 Apr 2020 09:51:22 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=mediatek.com header.i=@mediatek.com header.b="iNG2m24U" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B254620719 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=mediatek.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id EF6688E0019; Tue, 7 Apr 2020 05:51:21 -0400 (EDT) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id EA5148E0001; Tue, 7 Apr 2020 05:51:21 -0400 (EDT) X-Original-To: int-list-linux-mm@kvack.org X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id DBAA98E0019; Tue, 7 Apr 2020 05:51:21 -0400 (EDT) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0248.hostedemail.com [216.40.44.248]) by kanga.kvack.org (Postfix) with ESMTP id C22FC8E0001 for ; Tue, 7 Apr 2020 05:51:21 -0400 (EDT) Received: from smtpin08.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 70280127AB for ; Tue, 7 Apr 2020 09:51:21 +0000 (UTC) X-FDA: 76680591162.08.cause38_bb8236e78157 X-Spam-Summary: 2,0,0,303bc94910f467a5,d41d8cd98f00b204,miles.chen@mediatek.com,,RULES_HIT:41:355:379:541:800:960:973:988:989:1185:1260:1277:1311:1313:1314:1345:1437:1514:1515:1516:1518:1534:1541:1585:1711:1730:1747:1777:1792:2393:2559:2562:3138:3139:3140:3141:3142:3352:3867:3870:3871:3872:3874:4321:4605:5007:6261:6653:7901:10004:10400:11026:11473:11658:11914:12043:12296:12297:12521:12555:12679:12895:12986:13069:13311:13357:14096:14097:14181:14394:14721:21080:21451:21627:22047:30054:30070,0,RBL:210.61.82.184:@mediatek.com:.lbl8.mailshell.net-62.14.12.100 64.201.201.201,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:fp,MSBL:0,DNSBL:neutral,Custom_rules:0:0:0,LFtime:25,LUA_SUMMARY:none X-HE-Tag: cause38_bb8236e78157 X-Filterd-Recvd-Size: 3445 Received: from mailgw02.mediatek.com (unknown [210.61.82.184]) by imf26.hostedemail.com (Postfix) with ESMTP for ; Tue, 7 Apr 2020 09:51:20 +0000 (UTC) X-UUID: 5e6f45f9af8e4cba8c047962a43391fb-20200407 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=mediatek.com; s=dk; h=Content-Transfer-Encoding:Content-Type:MIME-Version:Message-ID:Date:Subject:CC:To:From; bh=XLhZCqqQ+XAe7Id+sLkm1mR2JnMwc/iwpAHwXkCFgUQ=; b=iNG2m24UbyP+zalcyLC9KtRSw+sVWZcos6iUdHCiqUfyRjX/A6WHvCt5MzK2MAaeH2s5WS0YR6d0KEiPRIf1RtdA2y2MG9I7Z2sXezcxqQiiYPdoyoxc2c9XMqFMiTI89LWTY55hBDqOpx+EfxjKpUvO7mtVsPyqbVWj/ac/v8I=; X-UUID: 5e6f45f9af8e4cba8c047962a43391fb-20200407 Received: from mtkcas06.mediatek.inc [(172.21.101.30)] by mailgw02.mediatek.com (envelope-from ) (Cellopoint E-mail Firewall v4.1.10 Build 0809 with TLS) with ESMTP id 269059542; Tue, 07 Apr 2020 17:51:14 +0800 Received: from mtkcas08.mediatek.inc (172.21.101.126) by mtkmbs06n2.mediatek.inc (172.21.101.130) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Tue, 7 Apr 2020 17:51:10 +0800 Received: from mtksdccf07.mediatek.inc (172.21.84.99) by mtkcas08.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.0.1497.2 via Frontend Transport; Tue, 7 Apr 2020 17:51:09 +0800 From: Miles Chen To: Andrew Morton CC: , , , , Miles Chen Subject: [PATCH] mm/gup: fix null pointer dereference detected by coverity Date: Tue, 7 Apr 2020 17:51:07 +0800 Message-ID: <20200407095107.1988-1-miles.chen@mediatek.com> X-Mailer: git-send-email 2.18.0 MIME-Version: 1.0 X-TM-SNTS-SMTP: F11F2E2A2FF92E73BAB9EDC1B554CE3E5CCB1D0ABAD6F0EF683C94EC7DB3A3AF2000:8 X-MTK: N X-Bogosity: Ham, tests=bogofilter, spamicity=0.001541, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: In fixup_user_fault(), it is possible that unlocked is NULL, so we should test unlocked before using it. For example, in arch/arc/kernel/process.c, NULL is passed to fixup_user_fault(). SYSCALL_DEFINE3(arc_usr_cmpxchg, int *, uaddr, int, expected, int, new) { ... ret = fixup_user_fault(current, current->mm, (unsigned long) uaddr, FAULT_FLAG_WRITE, NULL); ... } Fixes: 4a9e1cda2748 ("mm: bring in additional flag for fixup_user_fault to signal unlock") Signed-off-by: Miles Chen Reviewed-by: Ira Weiny Acked-by: Souptick Joarder --- mm/gup.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/mm/gup.c b/mm/gup.c index da3e03185144..a68d11dc232d 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -1230,7 +1230,8 @@ int fixup_user_fault(struct task_struct *tsk, struct mm_struct *mm, if (ret & VM_FAULT_RETRY) { down_read(&mm->mmap_sem); if (!(fault_flags & FAULT_FLAG_TRIED)) { - *unlocked = true; + if (unlocked) + *unlocked = true; fault_flags |= FAULT_FLAG_TRIED; goto retry; }