[PATCH 5.9 182/757] blk-mq: move cancel of hctx->run_work to the front of blk_exit_queue

Greg Kroah-Hartman
2020-10-27T15:58:40Z

From: Yang Yang <yang.yang@vivo.com>

[ Upstream commit 47ce030b7ac5a5259a9a5919f230b52497afc31a ]

blk_exit_queue will free elevator_data, while blk_mq_run_work_fn
will access it. Move cancel of hctx->run_work to the front of
blk_exit_queue to avoid use-after-free.

Fixes: 1b97871b501f ("blk-mq: move cancel of hctx->run_work into blk_mq_hw_sysfs_release")
Signed-off-by: Yang Yang <yang.yang@vivo.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
block/blk-mq-sysfs.c | 2 --
block/blk-sysfs.c | 9 ++++++++-
2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/block/blk-mq-sysfs.c b/block/blk-mq-sysfs.c
index 062229395a507..7b52e7657b2d1 100644
--- a/block/blk-mq-sysfs.c
+++ b/block/blk-mq-sysfs.c
@@ -36,8 +36,6 @@ static void blk_mq_hw_sysfs_release(struct kobject *kobj)
struct blk_mq_hw_ctx *hctx = container_of(kobj, struct blk_mq_hw_ctx,
kobj);

- cancel_delayed_work_sync(&hctx->run_work);
-
if (hctx->flags & BLK_MQ_F_BLOCKING)
cleanup_srcu_struct(hctx->srcu);
blk_free_flush_queue(hctx->fq);
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 7dda709f3ccb6..8c6bafc801dd9 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -934,9 +934,16 @@ static void blk_release_queue(struct kobject *kobj)

blk_free_queue_stats(q->stats);

- if (queue_is_mq(q))
+ if (queue_is_mq(q)) {
+ struct blk_mq_hw_ctx *hctx;
+ int i;
+
cancel_delayed_work_sync(&q->requeue_work);

+ queue_for_each_hw_ctx(q, hctx, i)
+ cancel_delayed_work_sync(&hctx->run_work);
+ }
+
blk_exit_queue(q);

blk_queue_free_zone_bitmaps(q);
--
2.25.1