diff options
author | Jan Kara <jack@suse.cz> | 2018-10-05 18:44:40 -0400 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-11-13 11:15:05 -0800 |
commit | cf08282805374fbf0c3c6a124f8e4687c21c6615 (patch) | |
tree | ec1b510c89103f2fab37f7ef16b18cbbecc089a0 /fs/gfs2 | |
parent | 97a063dfcbdf910bfe330c1ca53bd7c70ae1ae75 (diff) |
jbd2: fix use after free in jbd2_log_do_checkpoint()
commit ccd3c4373eacb044eb3832966299d13d2631f66f upstream.
The code cleaning transaction's lists of checkpoint buffers has a bug
where it increases bh refcount only after releasing
journal->j_list_lock. Thus the following race is possible:
CPU0 CPU1
jbd2_log_do_checkpoint()
jbd2_journal_try_to_free_buffers()
__journal_try_to_free_buffer(bh)
...
while (transaction->t_checkpoint_io_list)
...
if (buffer_locked(bh)) {
<-- IO completes now, buffer gets unlocked -->
spin_unlock(&journal->j_list_lock);
spin_lock(&journal->j_list_lock);
__jbd2_journal_remove_checkpoint(jh);
spin_unlock(&journal->j_list_lock);
try_to_free_buffers(page);
get_bh(bh) <-- accesses freed bh
Fix the problem by grabbing bh reference before unlocking
journal->j_list_lock.
Fixes: dc6e8d669cf5 ("jbd2: don't call get_bh() before calling __jbd2_journal_remove_checkpoint()")
Fixes: be1158cc615f ("jbd2: fold __process_buffer() into jbd2_log_do_checkpoint()")
Reported-by: syzbot+7f4a27091759e2fe7453@syzkaller.appspotmail.com
CC: stable@vger.kernel.org
Reviewed-by: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs/gfs2')
0 files changed, 0 insertions, 0 deletions