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=-2.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 BA8ABC3279B for ; Tue, 10 Jul 2018 18:35:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 88833208E8 for ; Tue, 10 Jul 2018 18:35:24 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 88833208E8 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linuxfoundation.org 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 S2389585AbeGJSff (ORCPT ); Tue, 10 Jul 2018 14:35:35 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:48302 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389566AbeGJSfe (ORCPT ); Tue, 10 Jul 2018 14:35:34 -0400 Received: from localhost (LFbn-1-12247-202.w90-92.abo.wanadoo.fr [90.92.61.202]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id AE70AE78; Tue, 10 Jul 2018 18:35:20 +0000 (UTC) From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Theodore Tso , Andreas Dilger , stable@kernel.org Subject: [PATCH 4.17 29/56] ext4: always verify the magic number in xattr blocks Date: Tue, 10 Jul 2018 20:25:11 +0200 Message-Id: <20180710182505.028507953@linuxfoundation.org> X-Mailer: git-send-email 2.18.0 In-Reply-To: <20180710182503.544433950@linuxfoundation.org> References: <20180710182503.544433950@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.17-stable review patch. If anyone has any objections, please let me know. ------------------ From: Theodore Ts'o commit 513f86d73855ce556ea9522b6bfd79f87356dc3a upstream. If there an inode points to a block which is also some other type of metadata block (such as a block allocation bitmap), the buffer_verified flag can be set when it was validated as that other metadata block type; however, it would make a really terrible external attribute block. The reason why we use the verified flag is to avoid constantly reverifying the block. However, it doesn't take much overhead to make sure the magic number of the xattr block is correct, and this will avoid potential crashes. This addresses CVE-2018-10879. https://bugzilla.kernel.org/show_bug.cgi?id=200001 Signed-off-by: Theodore Ts'o Reviewed-by: Andreas Dilger Cc: stable@kernel.org Signed-off-by: Greg Kroah-Hartman --- fs/ext4/xattr.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/fs/ext4/xattr.c +++ b/fs/ext4/xattr.c @@ -230,12 +230,12 @@ __ext4_xattr_check_block(struct inode *i { int error = -EFSCORRUPTED; - if (buffer_verified(bh)) - return 0; - if (BHDR(bh)->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC) || BHDR(bh)->h_blocks != cpu_to_le32(1)) goto errout; + if (buffer_verified(bh)) + return 0; + error = -EFSBADCRC; if (!ext4_xattr_block_csum_verify(inode, bh)) goto errout;