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=-9.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,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 9C76BC04E84 for ; Wed, 15 May 2019 11:40:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6E07720578 for ; Wed, 15 May 2019 11:40:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1557920401; bh=A2HWa2eMV8cNpLlt3TpLLCMT1YnL9BzX46XVNAsJMbk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=a+KkvLmIPgmxogM/KUmYdDXhPrSzhAbm7udAquQSYTnOBmWvNPIFDEFf0xb37ntJM 5DfJoIHDf7PukAifForhEQXJxdWDo56IOGh5NYoqq/QXJfmOytRYPqQmgqmbjWYeKM yRl9Z5eAN37oneJ23Zk+fVyxDUjDpbijW1+IQ/lA= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732336AbfEOL36 (ORCPT ); Wed, 15 May 2019 07:29:58 -0400 Received: from mail.kernel.org ([198.145.29.99]:41298 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726589AbfEOL3z (ORCPT ); Wed, 15 May 2019 07:29:55 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id A5A74206BF; Wed, 15 May 2019 11:29:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1557919794; bh=A2HWa2eMV8cNpLlt3TpLLCMT1YnL9BzX46XVNAsJMbk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=gsMIWM2qtrzIN07IT2uJdI7FyOpBP6H6AOeV1nvLrZ2mtWfJDEXkpZKxp2T9XkJXq e6qBs+exVuDuV9f0eSvuu2l1ZDqSzHzf78N/CawTx4O+Duq+s/C3YIGdfXVrEoVXEx ccYIQLhhRBHCUsJ1ZhZ+gsQrKOzo0vCb4eK3oZ+o= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Andrey Ryabinin , Mel Gorman , Andrew Morton , Linus Torvalds , Sasha Levin Subject: [PATCH 5.0 096/137] mm/page_alloc.c: avoid potential NULL pointer dereference Date: Wed, 15 May 2019 12:56:17 +0200 Message-Id: <20190515090700.506837533@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190515090651.633556783@linuxfoundation.org> References: <20190515090651.633556783@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org [ 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 eedb57f9b40b5..d59be95ba45cf 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