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=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS 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 2E0ECC433F4 for ; Sat, 22 Sep 2018 00:21:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DC5F42157C for ; Sat, 22 Sep 2018 00:21:42 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DC5F42157C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=decadent.org.uk Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2392047AbeIVGKs (ORCPT ); Sat, 22 Sep 2018 02:10:48 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:44231 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2391930AbeIVGKs (ORCPT ); Sat, 22 Sep 2018 02:10:48 -0400 Received: from [2a02:8011:400e:2:cbab:f00:c93f:614] (helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.84_2) (envelope-from ) id 1g3Vdy-0008Ba-3t; Sat, 22 Sep 2018 01:19:30 +0100 Received: from ben by deadeye with local (Exim 4.91) (envelope-from ) id 1g3Vdn-0000rm-VC; Sat, 22 Sep 2018 01:19:19 +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, "Theodore Ts'o" Date: Sat, 22 Sep 2018 01:15:42 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 26/63] ext4: verify the depth of extent tree in ext4_find_extent() In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:cbab:f00:c93f:614 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 3.16.58-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Theodore Ts'o commit bc890a60247171294acc0bd67d211fa4b88d40ba upstream. If there is a corupted file system where the claimed depth of the extent tree is -1, this can cause a massive buffer overrun leading to sadness. This addresses CVE-2018-10877. https://bugzilla.kernel.org/show_bug.cgi?id=199417 Signed-off-by: Theodore Ts'o [bwh: Backported to 3.16: return -EIO instead of -EFSCORRUPTED] Signed-off-by: Ben Hutchings --- fs/ext4/ext4_extents.h | 1 + fs/ext4/extents.c | 6 ++++++ 2 files changed, 7 insertions(+) --- a/fs/ext4/ext4_extents.h +++ b/fs/ext4/ext4_extents.h @@ -103,6 +103,7 @@ struct ext4_extent_header { }; #define EXT4_EXT_MAGIC cpu_to_le16(0xf30a) +#define EXT4_MAX_EXTENT_DEPTH 5 #define EXT4_EXTENT_TAIL_OFFSET(hdr) \ (sizeof(struct ext4_extent_header) + \ --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -851,6 +851,12 @@ ext4_ext_find_extent(struct inode *inode eh = ext_inode_hdr(inode); depth = ext_depth(inode); + if (depth < 0 || depth > EXT4_MAX_EXTENT_DEPTH) { + EXT4_ERROR_INODE(inode, "inode has invalid extent depth: %d", + depth); + ret = -EIO; + goto err; + } /* account possible depth increase */ if (!path) {