Searched hist:"22 aa66a3" (Results 1 – 1 of 1) sorted by relevance
/openbmc/linux/drivers/md/ |
H A D | dm-snap.c | 22aa66a3 Tue Feb 17 13:34:00 CST 2015 Mikulas Patocka <mpatocka@redhat.com> 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 22aa66a3 Tue Feb 17 13:34:00 CST 2015 Mikulas Patocka <mpatocka@redhat.com> 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
|