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49 lines
2.0 KiB
Diff
49 lines
2.0 KiB
Diff
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From 016a3592cc34fa349235b5a8b48af5cece2cbfeb Mon Sep 17 00:00:00 2001
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From: Theodore Ts'o <tytso@mit.edu>
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Date: Thu, 27 Dec 2012 01:42:50 -0500
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Subject: [PATCH] ext4: avoid hang when mounting non-journal filesystems with
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orphan list
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commit 0e9a9a1ad619e7e987815d20262d36a2f95717ca upstream.
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When trying to mount a file system which does not contain a journal,
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but which does have a orphan list containing an inode which needs to
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be truncated, the mount call with hang forever in
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ext4_orphan_cleanup() because ext4_orphan_del() will return
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immediately without removing the inode from the orphan list, leading
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to an uninterruptible loop in kernel code which will busy out one of
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the CPU's on the system.
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This can be trivially reproduced by trying to mount the file system
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found in tests/f_orphan_extents_inode/image.gz from the e2fsprogs
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source tree. If a malicious user were to put this on a USB stick, and
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mount it on a Linux desktop which has automatic mounts enabled, this
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could be considered a potential denial of service attack. (Not a big
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deal in practice, but professional paranoids worry about such things,
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and have even been known to allocate CVE numbers for such problems.)
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-js: This is a fix for CVE-2013-2015.
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Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
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Reviewed-by: Zheng Liu <wenqing.lz@taobao.com>
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Acked-by: Jan Kara <jack@suse.cz>
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Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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---
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fs/ext4/namei.c | 3 ++-
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1 file changed, 2 insertions(+), 1 deletion(-)
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diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
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index 9fb3fae4898a..54ad9a54cd89 100644
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--- a/fs/ext4/namei.c
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+++ b/fs/ext4/namei.c
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@@ -2054,7 +2054,8 @@ int ext4_orphan_del(handle_t *handle, struct inode *inode)
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int err = 0;
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/* ext4_handle_valid() assumes a valid handle_t pointer */
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- if (handle && !ext4_handle_valid(handle))
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+ if (handle && !ext4_handle_valid(handle) &&
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+ !(EXT4_SB(inode->i_sb)->s_mount_state & EXT4_ORPHAN_FS))
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return 0;
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mutex_lock(&EXT4_SB(inode->i_sb)->s_orphan_lock);
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