[PATCH 3.16 048/305] ext4: fix oops on corrupted filesystem

Ben Hutchings
2016-08-14T11:37:30Z

From: Jan Kara <jack@suse.cz>

commit 74177f55b70e2f2be770dd28684dd6d17106a4ba upstream.

When filesystem is corrupted in the right way, it can happen
ext4_mark_iloc_dirty() in ext4_orphan_add() returns error and we
subsequently remove inode from the in-memory orphan list. However this
deletion is done with list_del(&EXT4_I(inode)->i_orphan) and thus we
leave i_orphan list_head with a stale content. Later we can look at this
content causing list corruption, oops, or other issues. The reported
trace looked like:

WARNING: CPU: 0 PID: 46 at lib/list_debug.c:53 __list_del_entry+0x6b/0x100()
list_del corruption, 0000000061c1d6e0->next is LIST_POISON1
0000000000100100)
CPU: 0 PID: 46 Comm: ext4.exe Not tainted 4.1.0-rc4+ #250
Stack:
60462947 62219960 602ede24 62219960
602ede24 603ca293 622198f0 602f02eb
62219950 6002c12c 62219900 601b4d6b
Call Trace:
[<6005769c>] ? vprintk_emit+0x2dc/0x5c0
[<602ede24>] ? printk+0x0/0x94
[<600190bc>] show_stack+0xdc/0x1a0
[<602ede24>] ? printk+0x0/0x94
[<602ede24>] ? printk+0x0/0x94
[<602f02eb>] dump_stack+0x2a/0x2c
[<6002c12c>] warn_slowpath_common+0x9c/0xf0
[<601b4d6b>] ? __list_del_entry+0x6b/0x100
[<6002c254>] warn_slowpath_fmt+0x94/0xa0
[<602f4d09>] ? __mutex_lock_slowpath+0x239/0x3a0
[<6002c1c0>] ? warn_slowpath_fmt+0x0/0xa0
[<60023ebf>] ? set_signals+0x3f/0x50
[<600a205a>] ? kmem_cache_free+0x10a/0x180
[<602f4e88>] ? mutex_lock+0x18/0x30
[<601b4d6b>] __list_del_entry+0x6b/0x100
[<601177ec>] ext4_orphan_del+0x22c/0x2f0
[<6012f27c>] ? __ext4_journal_start_sb+0x2c/0xa0
[<6010b973>] ? ext4_truncate+0x383/0x390
[<6010bc8b>] ext4_write_begin+0x30b/0x4b0
[<6001bb50>] ? copy_from_user+0x0/0xb0
[<601aa840>] ? iov_iter_fault_in_readable+0xa0/0xc0
[<60072c4f>] generic_perform_write+0xaf/0x1e0
[<600c4166>] ? file_update_time+0x46/0x110
[<60072f0f>] __generic_file_write_iter+0x18f/0x1b0
[<6010030f>] ext4_file_write_iter+0x15f/0x470
[<60094e10>] ? unlink_file_vma+0x0/0x70
[<6009b180>] ? unlink_anon_vmas+0x0/0x260
[<6008f169>] ? free_pgtables+0xb9/0x100
[<600a6030>] __vfs_write+0xb0/0x130
[<600a61d5>] vfs_write+0xa5/0x170
[<600a63d6>] SyS_write+0x56/0xe0
[<6029fcb0>] ? __libc_waitpid+0x0/0xa0
[<6001b698>] handle_syscall+0x68/0x90
[<6002633d>] userspace+0x4fd/0x600
[<6002274f>] ? save_registers+0x1f/0x40
[<60028bd7>] ? arch_prctl+0x177/0x1b0
[<60017bd5>] fork_handler+0x85/0x90

Fix the problem by using list_del_init() as we always should with
i_orphan list.

Reported-by: Vegard Nossum <vegard.nossum@oracle.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
fs/ext4/namei.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -2626,7 +2626,7 @@ int ext4_orphan_add(handle_t *handle, st
* list entries can cause panics at unmount time.
*/
mutex_lock(&sbi->s_orphan_lock);
- list_del(&EXT4_I(inode)->i_orphan);
+ list_del_init(&EXT4_I(inode)->i_orphan);
mutex_unlock(&sbi->s_orphan_lock);
}
}