6.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Ming Lei <ming.lei@xxxxxxxxxx>
[ 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@xxxxxxxxxxxxxx>
Cc: Yu Kuai <yukuai3@xxxxxxxxxx>
Fixes: 2895f1831e91 ("nbd: don't clear 'NBD_CMD_INFLIGHT' flag if request is not completed")
Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
Reviewed-by: Yu Kuai <yukuai3@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20240830034145.1827742-1-ming.lei@xxxxxxxxxx
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
drivers/block/nbd.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 1089dc646b808..96b349148e578 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -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;
}
--
2.43.0
