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| author | Mikulas Patocka <mpatocka@redhat.com> | 2015-02-17 20:34:00 +0100 |
|---|---|---|
| committer | Mike Snitzer <snitzer@redhat.com> | 2015-02-18 15:41:54 +0100 |
| commit | 22aa66a3ee5b61e0f4a0bfeabcaa567861109ec3 (patch) | |
| tree | ff93a13145102951cdc5302462175db52979ecdd /drivers/md/dm-snap.c | |
| parent | dm: fix a race condition in dm_get_md (diff) | |
| download | linux-22aa66a3ee5b61e0f4a0bfeabcaa567861109ec3.tar.xz linux-22aa66a3ee5b61e0f4a0bfeabcaa567861109ec3.zip | |
dm snapshot: fix a possible invalid memory access on unload
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>
Cc: stable@vger.kernel.org
Diffstat (limited to 'drivers/md/dm-snap.c')
| -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) |