diff options
| author | Mikulas Patocka <mpatocka@redhat.com> | 2015-02-17 14:34:00 -0500 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2015-03-18 13:31:33 +0100 |
| commit | fe14b343fef97266686e7de566ba5bae0199a8b7 (patch) | |
| tree | cd574a23c09145a4f101cff05b04a537f7d5ee95 | |
| parent | 66c4b5173c0626f7a5a9b79cb4422926bdb439b4 (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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -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 ebddef5237e4..c356a10b9ba5 100644 --- a/drivers/md/dm-snap.c +++ b/drivers/md/dm-snap.c @@ -1440,8 +1440,6 @@ out: full_bio->bi_private = pe->full_bio_private; atomic_inc(&full_bio->bi_remaining); } - free_pending_exception(pe); - increment_pending_exceptions_done_count(); up_write(&s->lock); @@ -1458,6 +1456,8 @@ out: } retry_origin_bios(s, origin_bios); + + free_pending_exception(pe); } static void commit_callback(void *context, int success) |