From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:44900 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732703AbeGJS14 (ORCPT ); Tue, 10 Jul 2018 14:27:56 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Theodore Tso , stable@kernel.org Subject: [PATCH 4.4 26/47] ext4: verify the depth of extent tree in ext4_find_extent() Date: Tue, 10 Jul 2018 20:24:50 +0200 Message-Id: <20180710182338.244583513@linuxfoundation.org> In-Reply-To: <20180710182337.047502999@linuxfoundation.org> References: <20180710182337.047502999@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.4-stable 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 Cc: stable@kernel.org Signed-off-by: Greg Kroah-Hartman --- 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 @@ -876,6 +876,12 @@ ext4_find_extent(struct inode *inode, ex 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 = -EFSCORRUPTED; + goto err; + } if (path) { ext4_ext_drop_refs(path);