[PATCH V2 2/3] nvmet-tcp: fix a race condition between release_queue and io_work

Maurizio Lombardi
2021-11-15T16:32:11Z

If the initiator executes a reset controller operation while
performing I/O, the target kernel will crash because of a race condition
between release_queue and io_work;
nvmet_tcp_uninit_data_in_cmds() may be executed while io_work
is running, calling flush_work() was not sufficient to
prevent this because io_work could requeue itself.

Fix this bug by using cancel_work_sync() to prevent io_work
from requeuing itself and set rcv_state to NVMET_TCP_RECV_ERR to
make sure we don't receive any more data from the socket.

Signed-off-by: Maurizio Lombardi <mlombard@redhat.com>
---
drivers/nvme/target/tcp.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/nvme/target/tcp.c b/drivers/nvme/target/tcp.c
index 9aa81af84efa..028b47ff0f0f 100644
--- a/drivers/nvme/target/tcp.c
+++ b/drivers/nvme/target/tcp.c
@@ -1447,7 +1447,9 @@ static void nvmet_tcp_release_queue_work(struct work_struct *w)
mutex_unlock(&nvmet_tcp_queue_mutex);

nvmet_tcp_restore_socket_callbacks(queue);
- flush_work(&queue->io_work);
+ cancel_work_sync(&queue->io_work);
+ /* stop accepting incoming data */
+ queue->rcv_state = NVMET_TCP_RECV_ERR;

nvmet_tcp_uninit_data_in_cmds(queue);
nvmet_sq_destroy(&queue->nvme_sq);
--
2.27.0