6.11-stable review patch. If anyone has any objections, please let me know.
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From: Ming Lei ming.lei@redhat.com
[ 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: 2895f1831e91 ("nbd: don't clear 'NBD_CMD_INFLIGHT' flag if request is not completed") Signed-off-by: Ming Lei ming.lei@redhat.com Reviewed-by: Yu Kuai yukuai3@huawei.com Link: https://lore.kernel.org/r/20240830034145.1827742-1-ming.lei@redhat.com Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Sasha Levin sashal@kernel.org --- 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 41a90150b501d..69b9851b67982 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); } @@ -488,8 +499,8 @@ 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; }