[PATCH] block, bfq: fix UAF problem in bfqg_stats_init()

[PATCH] block, bfq: fix UAF problem in bfqg_stats_init()

[Zheng Liang]

In bfq_pd_alloc(), the function bfqg_stats_init() init bfqg. If
blkg_rwstat_init() init bytes successful and init ios failed,
bfqg_stats_init() return failed, bfqg will be freed. If we traverse
the list of percpu_counters, It will have use after free problem.

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

Fixes: commit fd41e60331b ("bfq-iosched: stop using blkg->stat_bytes and ->stat_ios")
Signed-off-by: Zheng Liang <zhengliang6@huawei.com>
---
 block/bfq-cgroup.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c
index e2f14508f2d6..243ffbc1f106 100644
--- a/block/bfq-cgroup.c
+++ b/block/bfq-cgroup.c
@@ -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)
-- 
2.25.4

[PATCH] block, bfq: fix UAF problem in bfqg_stats_init()

[Zheng Liang]

In bfq_pd_alloc(), the function bfqg_stats_init() init bfqg. If
blkg_rwstat_init() init bytes successful and init ios failed,
bfqg_stats_init() return failed, bfqg will be freed. If we traverse
the list of percpu_counters, It will have use after free problem.

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

Fixes: commit fd41e60331b ("bfq-iosched: stop using blkg->stat_bytes and ->stat_ios")
Signed-off-by: Zheng Liang <zhengliang6-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
---
 block/bfq-cgroup.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c
index e2f14508f2d6..243ffbc1f106 100644
--- a/block/bfq-cgroup.c
+++ b/block/bfq-cgroup.c
@@ -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)
-- 
2.25.4