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 14:11:07 +0100 |
| commit | 0a694d185c0856800f7045b9621a50b704c7302d (patch) | |
| tree | 6c87d2ec96ae076961c509b1622dce5a70f2794d | |
| parent | e6bafcd14630f6fd84a326f1d51ce1466dfd60df (diff) | |
| download | linux-stable-0a694d185c0856800f7045b9621a50b704c7302d.tar.gz | |
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 864b03f47727..8b204ae216ab 100644 --- a/drivers/md/dm-snap.c +++ b/drivers/md/dm-snap.c @@ -1432,8 +1432,6 @@ 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); @@ -1450,6 +1448,8 @@ out: } retry_origin_bios(s, origin_bios); + + free_pending_exception(pe); } static void commit_callback(void *context, int success) |