block: fix use-after-free bug in blk throttle code
blk_throtl_exit() frees the throttle data hanging off the queue
in blk_cleanup_queue(), but blk_put_queue() will indirectly
dereference this data when calling blk_sync_queue() which in
turns calls throtl_shutdown_timer_wq().
Fix this by moving the freeing of the throttle data to when
the queue is truly being released, and post the call to
blk_sync_queue().
Reported-by: Ingo Molnar <mingo@elte.hu>
Tested-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
diff --git a/block/blk-core.c b/block/blk-core.c
index 4514146..51efd83 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -462,8 +462,6 @@
if (q->elevator)
elevator_exit(q->elevator);
- blk_throtl_exit(q);
-
blk_put_queue(q);
}
EXPORT_SYMBOL(blk_cleanup_queue);
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index da8a8a4..013457f 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -471,6 +471,8 @@
blk_sync_queue(q);
+ blk_throtl_exit(q);
+
if (rl->rq_pool)
mempool_destroy(rl->rq_pool);