Commit da9f3025 authored Apr 01, 2022 by Jan Kara Committed by Greg Kroah-Hartman Jun 14, 2022

bfq: Update cgroup information before merging bio



commit ea591cd4eb270393810e7be01feb8fde6a34fbbe upstream.

When the process is migrated to a different cgroup (or in case of
writeback just starts submitting bios associated with a different
cgroup) bfq_merge_bio() can operate with stale cgroup information in
bic. Thus the bio can be merged to a request from a different cgroup or
it can result in merging of bfqqs for different cgroups or bfqqs of
already dead cgroups and causing possible use-after-free issues. Fix the
problem by updating cgroup information in bfq_merge_bio().

CC: stable@vger.kernel.org
Fixes: e21b7a0b ("block, bfq: add full hierarchical scheduling and cgroups support")
Tested-by: "yukuai (C)" <yukuai3@huawei.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20220401102752.8599-4-jack@suse.cz


Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 31326bf5

block/bfq-iosched.c

+9 −2

Original line number	Diff line number	Diff line
		@@ -2227,10 +2227,17 @@ static bool bfq_bio_merge(struct request_queue q, struct bio bio,

		spin_lock_irq(&bfqd->lock);

		if (bic)
		if (bic) {
		/*
		* Make sure cgroup info is uptodate for current process before
		* considering the merge.
		*/
		bfq_bic_update_cgroup(bic, bio);

		bfqd->bio_bfqq = bic_to_bfqq(bic, op_is_sync(bio->bi_opf));
		else
		} else {
		bfqd->bio_bfqq = NULL;
		}
		bfqd->bio_bic = bic;

		ret = blk_mq_sched_try_merge(q, bio, nr_segs, &free);