Commit 2fc428f6 authored by Zheng Liang's avatar Zheng Liang Committed by Jens Axboe
Browse files

block, bfq: fix UAF problem in bfqg_stats_init() 



In bfq_pd_alloc(), the function bfqg_stats_init() init bfqg. If
blkg_rwstat_init() init bfqg_stats->bytes successful and init
bfqg_stats->ios failed, bfqg_stats_init() return failed, bfqg will
be freed. But blkg_rwstat->cpu_cnt is not deleted from the list of
percpu_counters. If we traverse the list of percpu_counters, It will
have UAF problem.

we should use blkg_rwstat_exit() to cleanup bfqg_stats bytes in the
above scenario.

Fixes: commit fd41e603 ("bfq-iosched: stop using blkg->stat_bytes and ->stat_ios")
Signed-off-by: default avatarZheng Liang <zhengliang6@huawei.com>
Acked-by: default avatarTejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20211018024225.1493938-1-zhengliang6@huawei.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent a808a9d5

block/bfq-cgroup.c

+7 −5
Original line number Diff line number Diff line
@@ -463,7 +463,7 @@ static int bfqg_stats_init(struct bfqg_stats *stats, gfp_t gfp) 
{

	if (blkg_rwstat_init(&stats->bytes, gfp) ||

	    blkg_rwstat_init(&stats->ios, gfp))

		return -ENOMEM;

		goto error;



#ifdef CONFIG_BFQ_CGROUP_DEBUG

	if (blkg_rwstat_init(&stats->merged, gfp) ||
@@ -476,13 +476,15 @@ static int bfqg_stats_init(struct bfqg_stats *stats, gfp_t gfp) 
	    bfq_stat_init(&stats->dequeue, gfp) ||

	    bfq_stat_init(&stats->group_wait_time, gfp) ||

	    bfq_stat_init(&stats->idle_time, gfp) ||

	    bfq_stat_init(&stats->empty_time, gfp)) {

		bfqg_stats_exit(stats);

		return -ENOMEM;

	}

	    bfq_stat_init(&stats->empty_time, gfp))

		goto error;

#endif



	return 0;



error:

	bfqg_stats_exit(stats);

	return -ENOMEM;

}



static struct bfq_group_data *cpd_to_bfqgd(struct blkcg_policy_data *cpd)