Commit f42d79ab authored Oct 14, 2015 by Junichi Nomura Committed by Jens Axboe Oct 15, 2015

blk-mq: fix use-after-free in blk_mq_free_tag_set()



tags is freed in blk_mq_free_rq_map() and should not be used after that.
The problem doesn't manifest if CONFIG_CPUMASK_OFFSTACK is false because
free_cpumask_var() is nop.

tags->cpumask is allocated in blk_mq_init_tags() so it's natural to
free cpumask in its counter part, blk_mq_free_tags().

Fixes: f26cdc85 ("blk-mq: Shared tag enhancements")
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Cc: Keith Busch <keith.busch@intel.com>
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

parent 835da3f9

block/blk-mq-tag.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -641,6 +641,7 @@ void blk_mq_free_tags(struct blk_mq_tags *tags)
		{
		bt_free(&tags->bitmap_tags);
		bt_free(&tags->breserved_tags);
		free_cpumask_var(tags->cpumask);
		kfree(tags);
		}

block/blk-mq.c

+1 −3

Original line number	Diff line number	Diff line
		@@ -2296,10 +2296,8 @@ void blk_mq_free_tag_set(struct blk_mq_tag_set *set)
		int i;

		for (i = 0; i < set->nr_hw_queues; i++) {
		if (set->tags[i]) {
		if (set->tags[i])
		blk_mq_free_rq_map(set, set->tags[i], i);
		free_cpumask_var(set->tags[i]->cpumask);
		}
		}

		kfree(set->tags);