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=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED 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 074AEC169C4 for ; Sun, 3 Feb 2019 13:53:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D6DF5218F0 for ; Sun, 3 Feb 2019 13:53:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728526AbfBCNuN (ORCPT ); Sun, 3 Feb 2019 08:50:13 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:52988 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727984AbfBCNtq (ORCPT ); Sun, 3 Feb 2019 08:49:46 -0500 Received: from cable-78.29.236.164.coditel.net ([78.29.236.164] helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1gqI9Y-0003wD-3H; Sun, 03 Feb 2019 13:49:44 +0000 Received: from ben by deadeye with local (Exim 4.92-RC4) (envelope-from ) id 1gqI9Y-0006xc-4a; Sun, 03 Feb 2019 14:49:44 +0100 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, Denis Kirjanov , "Filipe Manana" , "Liu Bo" , "David Sterba" Date: Sun, 03 Feb 2019 14:45:08 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) X-Patchwork-Hint: ignore Subject: [PATCH 3.16 097/305] Btrfs: fix null pointer dereference on compressed write path error In-Reply-To: X-SA-Exim-Connect-IP: 78.29.236.164 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.63-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Filipe Manana commit 3527a018c00e5dbada2f9d7ed5576437b6dd5cfb upstream. At inode.c:compress_file_range(), under the "free_pages_out" label, we can end up dereferencing the "pages" pointer when it has a NULL value. This case happens when "start" has a value of 0 and we fail to allocate memory for the "pages" pointer. When that happens we jump to the "cont" label and then enter the "if (start == 0)" branch where we immediately call the cow_file_range_inline() function. If that function returns 0 (success creating an inline extent) or an error (like -ENOMEM for example) we jump to the "free_pages_out" label and then access "pages[i]" leading to a NULL pointer dereference, since "nr_pages" has a value greater than zero at that point. Fix this by setting "nr_pages" to 0 when we fail to allocate memory for the "pages" pointer. Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=201119 Fixes: 771ed689d2cd ("Btrfs: Optimize compressed writeback and reads") Reviewed-by: Liu Bo Signed-off-by: Filipe Manana Reviewed-by: David Sterba Signed-off-by: David Sterba Signed-off-by: Ben Hutchings --- fs/btrfs/inode.c | 1 + 1 file changed, 1 insertion(+) --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -452,6 +452,7 @@ again: pages = kzalloc(sizeof(struct page *) * nr_pages, GFP_NOFS); if (!pages) { /* just bail out to the uncompressed code */ + nr_pages = 0; goto cont; }