diff options
| author | Mikulas Patocka <mpatocka@redhat.com> | 2015-02-17 14:34:00 -0500 |
|---|---|---|
| committer | Jiri Slaby <jslaby@suse.cz> | 2015-03-16 14:58:18 +0100 |
| commit | dde15ae3c9adb46ba366ffab34487080e1bb2a22 (patch) | |
| tree | c03c8b0adcd33d6fa7eb885bc18988fdbd110432 | |
| parent | 0a21fde3fe39835289f69d2280a68d570f611824 (diff) | |
dm snapshot: fix a possible invalid memory access on unload
commit 22aa66a3ee5b61e0f4a0bfeabcaa567861109ec3 upstream.
When the snapshot target is unloaded, snapshot_dtr() waits until
pending_exceptions_count drops to zero. Then, it destroys the snapshot.
Therefore, the function that decrements pending_exceptions_count
should not touch the snapshot structure after the decrement.
pending_complete() calls free_pending_exception(), which decrements
pending_exceptions_count, and then it performs up_write(&s->lock) and it
calls retry_origin_bios() which dereferences s->origin. These two
memory accesses to the fields of the snapshot may touch the dm_snapshot
struture after it is freed.
This patch moves the call to free_pending_exception() to the end of
pending_complete(), so that the snapshot will not be destroyed while
pending_complete() is in progress.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
| -rw-r--r-- | drivers/md/dm-snap.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c index 944690bafd93..d892a05c84f4 100644 --- a/drivers/md/dm-snap.c +++ b/drivers/md/dm-snap.c @@ -1439,8 +1439,6 @@ out: full_bio->bi_end_io = pe->full_bio_end_io; full_bio->bi_private = pe->full_bio_private; } - free_pending_exception(pe); - increment_pending_exceptions_done_count(); up_write(&s->lock); @@ -1457,6 +1455,8 @@ out: } retry_origin_bios(s, origin_bios); + + free_pending_exception(pe); } static void commit_callback(void *context, int success) |