Commit 50e3452c authored by Ming Lei's avatar Ming Lei Committed by Zheng Qixing
Browse files

nbd: fix race between timeout and normal completion 

stable inclusion
from stable-v6.6.54
commit 6e73b946a379a1dfbb62626af93843bdfb53753d
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/IAYQRD
CVE: CVE-2024-49855

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=6e73b946a379a1dfbb62626af93843bdfb53753d



--------------------------------

[ Upstream commit c9ea57c91f03bcad415e1a20113bdb2077bcf990 ]

If request timetout is handled by nbd_requeue_cmd(), normal completion
has to be stopped for avoiding to complete this requeued request, other
use-after-free can be triggered.

Fix the race by clearing NBD_CMD_INFLIGHT in nbd_requeue_cmd(), meantime
make sure that cmd->lock is grabbed for clearing the flag and the
requeue.

Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Yu Kuai <yukuai3@huawei.com>
Fixes: 2895f183 ("nbd: don't clear 'NBD_CMD_INFLIGHT' flag if request is not completed")
Signed-off-by: default avatarMing Lei <ming.lei@redhat.com>
Reviewed-by: default avatarYu Kuai <yukuai3@huawei.com>
Link: https://lore.kernel.org/r/20240830034145.1827742-1-ming.lei@redhat.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
Signed-off-by: default avatarZhangPeng <zhangpeng362@huawei.com>
Signed-off-by: default avatarZheng Qixing <zhengqixing@huawei.com>
parent 43acbd37

drivers/block/nbd.c

+12 −1
Original line number Diff line number Diff line
@@ -181,6 +181,17 @@ static void nbd_requeue_cmd(struct nbd_cmd *cmd) 
{

	struct request *req = blk_mq_rq_from_pdu(cmd);



	lockdep_assert_held(&cmd->lock);



	/*

	 * Clear INFLIGHT flag so that this cmd won't be completed in

	 * normal completion path

	 *

	 * INFLIGHT flag will be set when the cmd is queued to nbd next

	 * time.

	 */

	__clear_bit(NBD_CMD_INFLIGHT, &cmd->flags);



	if (!test_and_set_bit(NBD_CMD_REQUEUED, &cmd->flags))

		blk_mq_requeue_request(req, true);

}
@@ -461,8 +472,8 @@ static enum blk_eh_timer_return nbd_xmit_timeout(struct request *req) 
					nbd_mark_nsock_dead(nbd, nsock, 1);

				mutex_unlock(&nsock->tx_lock);

			}

			mutex_unlock(&cmd->lock);

			nbd_requeue_cmd(cmd);

			mutex_unlock(&cmd->lock);

			nbd_config_put(nbd);

			return BLK_EH_DONE;

		}