linux-kernel - [PATCH v2 2/6] blk-mq: Fix use after of free q->mq

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Thu,  2 Jul 2015 23:29:53 +0900
From:	Akinobu Mita <akinobu.mita@...il.com>
To:	linux-kernel@...r.kernel.org
Cc:	Akinobu Mita <akinobu.mita@...il.com>,
	Jens Axboe <axboe@...nel.dk>, Ming Lei <tom.leiming@...il.com>
Subject: [PATCH v2 2/6] blk-mq: Fix use after of free q->mq_map

CPU hotplug handling for blk-mq (blk_mq_queue_reinit) updates
q->mq_map by blk_mq_update_queue_map() for all request queues in
all_q_list.  On the other hand, q->mq_map is released before deleting
the queue from all_q_list.

So if CPU hotplug event occurs in the window, invalid memory access
can happen.  Fix it by releasing q->mq_map in blk_mq_release() to make
it happen latter than removal from all_q_list.

Signed-off-by: Akinobu Mita <akinobu.mita@...il.com>
Suggested-by: Ming Lei <tom.leiming@...il.com>
Cc: Jens Axboe <axboe@...nel.dk>
Cc: Ming Lei <tom.leiming@...il.com>
---
 block/blk-mq.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index f537796..c5da908 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1928,6 +1928,9 @@ void blk_mq_release(struct request_queue *q)
 		kfree(hctx);
 	}
 
+	kfree(q->mq_map);
+	q->mq_map = NULL;
+
 	kfree(q->queue_hw_ctx);
 
 	/* ctx kobj stays in queue_ctx */
@@ -2073,11 +2076,6 @@ void blk_mq_free_queue(struct request_queue *q)
 	blk_mq_free_hw_queues(q, set);
 
 	percpu_ref_exit(&q->mq_usage_counter);
-
-	kfree(q->mq_map);
-
-	q->mq_map = NULL;
-
 	mutex_lock(&all_q_mutex);
 	list_del_init(&q->all_q_node);
 	mutex_unlock(&all_q_mutex);
-- 
1.9.1

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/