Sahitya Tummala 4be3eda04a ext4: fix use-after-free in dx_release()
commit 08fc98a4d6424af66eb3ac4e2cedd2fc927ed436 upstream.

The buffer_head (frames[0].bh) and it's corresping page can be
potentially free'd once brelse() is done inside the for loop
but before the for loop exits in dx_release(). It can be free'd
in another context, when the page cache is flushed via
drop_caches_sysctl_handler(). This results into below data abort
when accessing info->indirect_levels in dx_release().

Unable to handle kernel paging request at virtual address ffffffc17ac3e01e
Call trace:
 dx_release+0x70/0x90
 ext4_htree_fill_tree+0x2d4/0x300
 ext4_readdir+0x244/0x6f8
 iterate_dir+0xbc/0x160
 SyS_getdents64+0x94/0x174

Signed-off-by: Sahitya Tummala <stummala@codeaurora.org>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Cc: stable@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-05-21 18:50:20 +02:00
..
2018-07-08 15:30:51 +02:00
2019-05-16 19:42:30 +02:00
2018-12-17 09:28:54 +01:00
2018-12-21 14:13:04 +01:00
2017-09-04 19:05:15 -04:00
2017-04-17 12:52:27 -04:00
2019-03-13 14:03:11 -07:00