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=-9.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS, T_DKIMWL_WL_HIGH,URIBL_BLOCKED,USER_AGENT_GIT 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 072DBC004C9 for ; Tue, 7 May 2019 06:02:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BD297205C9 for ; Tue, 7 May 2019 06:02:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1557208937; bh=BS8bQZGoB7uxBqsmLwt1/UFGaXwyTwZEytlGNIEdKnU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=au2gFw4AO+IP9ThU3AUaeWzWTJ966yh8LeX+MS5hpuMymaQQiJKxy2DbZnZ4J9aTg FT0uFwC9h6N/KgytzDg23MTKprZZ9AqoYMCzceomilS3F91Coy8L5lsyOhtkkhGKya 8JW43idoqCbb494VBAJTwNamg1mtNPO4MUG8jp1s= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727023AbfEGGCQ (ORCPT ); Tue, 7 May 2019 02:02:16 -0400 Received: from mail.kernel.org ([198.145.29.99]:55706 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726650AbfEGFfl (ORCPT ); Tue, 7 May 2019 01:35:41 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id E85EB2087F; Tue, 7 May 2019 05:35:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1557207340; bh=BS8bQZGoB7uxBqsmLwt1/UFGaXwyTwZEytlGNIEdKnU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=iTyCt+hhs6WDmtMI27GEtirrF94M2dzJBG21bV7pKRoMyZwvzfdt0IrdEKf7521xO LsWbUzjZ/+5pBbKmUYxrzFTErGpOfV5rvoDAtwpz+74akzA+kQa2pTXPy/IJFpOH9J MdZtf/xco6k/fMksoHQil6jQtOxk9plagM56F9Tg= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Andrey Ryabinin , Mel Gorman , Andrew Morton , Linus Torvalds , Sasha Levin , linux-mm@kvack.org Subject: [PATCH AUTOSEL 5.0 95/99] mm/page_alloc.c: avoid potential NULL pointer dereference Date: Tue, 7 May 2019 01:32:29 -0400 Message-Id: <20190507053235.29900-95-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190507053235.29900-1-sashal@kernel.org> References: <20190507053235.29900-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Andrey Ryabinin [ Upstream commit 8139ad043d632c0e9e12d760068a7a8e91659aa1 ] ac.preferred_zoneref->zone passed to alloc_flags_nofragment() can be NULL. 'zone' pointer unconditionally derefernced in alloc_flags_nofragment(). Bail out on NULL zone to avoid potential crash. Currently we don't see any crashes only because alloc_flags_nofragment() has another bug which allows compiler to optimize away all accesses to 'zone'. Link: http://lkml.kernel.org/r/20190423120806.3503-1-aryabinin@virtuozzo.com Fixes: 6bb154504f8b ("mm, page_alloc: spread allocations across zones before introducing fragmentation") Signed-off-by: Andrey Ryabinin Acked-by: Mel Gorman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin --- mm/page_alloc.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index eedb57f9b40b..d59be95ba45c 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -3385,6 +3385,9 @@ alloc_flags_nofragment(struct zone *zone, gfp_t gfp_mask) alloc_flags |= ALLOC_KSWAPD; #ifdef CONFIG_ZONE_DMA32 + if (!zone) + return alloc_flags; + if (zone_idx(zone) != ZONE_NORMAL) goto out; -- 2.20.1