Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755935AbaBEUT5 (ORCPT ); Wed, 5 Feb 2014 15:19:57 -0500 Received: from mail.windriver.com ([147.11.1.11]:55523 "EHLO mail.windriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932366AbaBEUHo (ORCPT ); Wed, 5 Feb 2014 15:07:44 -0500 From: Paul Gortmaker To: , CC: "Theodore Ts'o" , Paul Gortmaker Subject: [v2.6.34-stable 182/213] ext4: avoid hang when mounting non-journal filesystems with orphan list Date: Wed, 5 Feb 2014 15:02:17 -0500 Message-ID: <1391630568-49251-183-git-send-email-paul.gortmaker@windriver.com> X-Mailer: git-send-email 1.8.5.2 In-Reply-To: <1391630568-49251-1-git-send-email-paul.gortmaker@windriver.com> References: <1391630568-49251-1-git-send-email-paul.gortmaker@windriver.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Theodore Ts'o ------------------- This is a commit scheduled for the next v2.6.34 longterm release. http://git.kernel.org/?p=linux/kernel/git/paulg/longterm-queue-2.6.34.git If you see a problem with using this for longterm, please comment. ------------------- commit 0e9a9a1ad619e7e987815d20262d36a2f95717ca upstream. When trying to mount a file system which does not contain a journal, but which does have a orphan list containing an inode which needs to be truncated, the mount call with hang forever in ext4_orphan_cleanup() because ext4_orphan_del() will return immediately without removing the inode from the orphan list, leading to an uninterruptible loop in kernel code which will busy out one of the CPU's on the system. This can be trivially reproduced by trying to mount the file system found in tests/f_orphan_extents_inode/image.gz from the e2fsprogs source tree. If a malicious user were to put this on a USB stick, and mount it on a Linux desktop which has automatic mounts enabled, this could be considered a potential denial of service attack. (Not a big deal in practice, but professional paranoids worry about such things, and have even been known to allocate CVE numbers for such problems.) Signed-off-by: "Theodore Ts'o" Reviewed-by: Zheng Liu Signed-off-by: Paul Gortmaker --- fs/ext4/namei.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c index d64e5f4f12ed..f501bdf9d4c1 100644 --- a/fs/ext4/namei.c +++ b/fs/ext4/namei.c @@ -2081,7 +2081,8 @@ int ext4_orphan_del(handle_t *handle, struct inode *inode) struct ext4_iloc iloc; int err = 0; - if (!EXT4_SB(inode->i_sb)->s_journal) + if ((!EXT4_SB(inode->i_sb)->s_journal) && + !(EXT4_SB(inode->i_sb)->s_mount_state & EXT4_ORPHAN_FS)) return 0; mutex_lock(&EXT4_SB(inode->i_sb)->s_orphan_lock); -- 1.8.5.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/