2021-10-22 08:19:18

by John Garry

Subject: [PATCH] blk-mq-sched: Don't reference queue tagset in blk_mq_sched_tags_teardown()

We should not reference the queue tagset in blk_mq_sched_tags_teardown()
(see function comment) for the blk-mq flags, so use the passed flags
instead.

This solves a use-after-free, similarly fixed earlier (and since broken
again) in commit f0c1c4d2864e ("blk-mq: fix use-after-free in
blk_mq_exit_sched").

Reported-by: Linux Kernel Functional Testing <[email protected]>
Reported-by: Naresh Kamboju <[email protected]>
Tested-by: Anders Roxell <[email protected]>
Fixes: e155b0c238b2 ("blk-mq: Use shared tags for shared sbitmap support")
Signed-off-by: John Garry <[email protected]>

diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index e85b7556b096..6a9444848e3a 100644
--- a/block/blk-mq-sched.c
+++ b/block/blk-mq-sched.c
@@ -541,7 +541,7 @@ static void blk_mq_sched_tags_teardown(struct request_queue *q, unsigned int fla

queue_for_each_hw_ctx(q, hctx, i) {
if (hctx->sched_tags) {
- if (!blk_mq_is_shared_tags(q->tag_set->flags))
+ if (!blk_mq_is_shared_tags(flags))
blk_mq_free_rq_map(hctx->sched_tags);
hctx->sched_tags = NULL;
}
--
2.17.1

2021-10-22 15:18:57

by Jens Axboe

Subject: Re: [PATCH] blk-mq-sched: Don't reference queue tagset in blk_mq_sched_tags_teardown()

On Fri, 22 Oct 2021 16:12:20 +0800, John Garry wrote:
> We should not reference the queue tagset in blk_mq_sched_tags_teardown()
> (see function comment) for the blk-mq flags, so use the passed flags
> instead.
>
> This solves a use-after-free, similarly fixed earlier (and since broken
> again) in commit f0c1c4d2864e ("blk-mq: fix use-after-free in
> blk_mq_exit_sched").
>
> [...]

Applied, thanks!

[1/1] blk-mq-sched: Don't reference queue tagset in blk_mq_sched_tags_teardown()
commit: 8bdf7b3fe1f48a2c1c212d4685903bba01409c0e

Best regards,
--
Jens Axboe