From: John Garry <john.garry@huawei.com>
Date: Fri, 22 Oct 2021 16:12:20 +0800
Subject: [PATCH] blk-mq-sched: Don't reference queue tagset in
 blk_mq_sched_tags_teardown()
Git-commit: 8bdf7b3fe1f48a2c1c212d4685903bba01409c0e
Patch-mainline: v5.16-rc1
References: jsc#PED-1183

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 <lkft@linaro.org>
Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Tested-by: Anders Roxell <anders.roxell@linaro.org>
Fixes: e155b0c238b2 ("blk-mq: Use shared tags for shared sbitmap support")
Signed-off-by: John Garry <john.garry@huawei.com>
Link: https://lore.kernel.org/r/1634890340-15432-1-git-send-email-john.garry@huawei.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Acked-by: Hannes Reinecke <hare@suse.com>
---
 block/blk-mq-sched.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index 5b259fdea794..c62b966dfaba 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;
 		}
-- 
2.35.3