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[209.132.180.67]) by mx.google.com with ESMTP id h34si6519538ede.247.2019.10.27.14.29.28; Sun, 27 Oct 2019 14:29:51 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b=XQaZCiOr; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732402AbfJ0VX4 (ORCPT + 99 others); Sun, 27 Oct 2019 17:23:56 -0400 Received: from mail.kernel.org ([198.145.29.99]:45270 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732371AbfJ0VXw (ORCPT ); Sun, 27 Oct 2019 17:23:52 -0400 Received: from localhost (100.50.158.77.rev.sfr.net [77.158.50.100]) (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 EEA9921726; Sun, 27 Oct 2019 21:23:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1572211431; bh=QTc0j71iag6ZSm7a9ZVdtJ4mG3TfhcPEhYId6nEPt3Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=XQaZCiOrrmJ4AwsJuHXz7rox4v6yBr/HHdokBobEApuBATseh7nc3Jf1X8CigerAq JibgEYyUjZFmZVtkBmY4zX185b3KGfSX2VJUpvaql/vyHQaAf+jdKSoEY4OD3lnoxS ZmwYUcV8/IgRTraaeUqO/TcZDBoPWNmXJBhTubE0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Vlastimil Babka , Florian Weimer , Dave Chinner , Mel Gorman , Andrew Morton , Linus Torvalds Subject: [PATCH 5.3 150/197] mm, compaction: fix wrong pfn handling in __reset_isolation_pfn() Date: Sun, 27 Oct 2019 22:01:08 +0100 Message-Id: <20191027203359.790853283@linuxfoundation.org> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20191027203351.684916567@linuxfoundation.org> References: <20191027203351.684916567@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Vlastimil Babka commit a2e9a5afce080226edbf1882d63d99bf32070e9e upstream. Florian and Dave reported [1] a NULL pointer dereference in __reset_isolation_pfn(). While the exact cause is unclear, staring at the code revealed two bugs, which might be related. One bug is that if zone starts in the middle of pageblock, block_page might correspond to different pfn than block_pfn, and then the pfn_valid_within() checks will check different pfn's than those accessed via struct page. This might result in acessing an unitialized page in CONFIG_HOLES_IN_ZONE configs. The other bug is that end_page refers to the first page of next pageblock and not last page of current pageblock. The online and valid check is then wrong and with sections, the while (page < end_page) loop might wander off actual struct page arrays. [1] https://lore.kernel.org/linux-xfs/87o8z1fvqu.fsf@mid.deneb.enyo.de/ Link: http://lkml.kernel.org/r/20191008152915.24704-1-vbabka@suse.cz Fixes: 6b0868c820ff ("mm/compaction.c: correct zone boundary handling when resetting pageblock skip hints") Signed-off-by: Vlastimil Babka Reported-by: Florian Weimer Reported-by: Dave Chinner Acked-by: Mel Gorman Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/compaction.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) --- a/mm/compaction.c +++ b/mm/compaction.c @@ -270,14 +270,15 @@ __reset_isolation_pfn(struct zone *zone, /* Ensure the start of the pageblock or zone is online and valid */ block_pfn = pageblock_start_pfn(pfn); - block_page = pfn_to_online_page(max(block_pfn, zone->zone_start_pfn)); + block_pfn = max(block_pfn, zone->zone_start_pfn); + block_page = pfn_to_online_page(block_pfn); if (block_page) { page = block_page; pfn = block_pfn; } /* Ensure the end of the pageblock or zone is online and valid */ - block_pfn += pageblock_nr_pages; + block_pfn = pageblock_end_pfn(pfn) - 1; block_pfn = min(block_pfn, zone_end_pfn(zone) - 1); end_page = pfn_to_online_page(block_pfn); if (!end_page) @@ -303,7 +304,7 @@ __reset_isolation_pfn(struct zone *zone, page += (1 << PAGE_ALLOC_COSTLY_ORDER); pfn += (1 << PAGE_ALLOC_COSTLY_ORDER); - } while (page < end_page); + } while (page <= end_page); return false; }