Fw: [PATCH] nvmet-tcp: fix race between ICReq handling and queue teardown

[Shivam Kumar]

_______________________________________
> From: Chaitanya Kulkarni <kch at nvidia.com>
> Sent: 08 April 2026 03:51
> To: Shivam Kumar
> Cc: hch at lst.de; sagi at grimberg.me; linux-nvme at lists.infradead.org; kbusch at kernel.org; Chaitanya Kulkarni; stable at vger.kernel.org
> Subject: [PATCH] nvmet-tcp: fix race between ICReq handling and queue teardown
>
> nvmet_tcp_handle_icreq() updates queue->state after sending an
> Initialization Connection Response (ICResp), but it does so without
> serializing against target-side queue teardown.
>
> If an NVMe/TCP host sends an Initialization Connection Request
> (ICReq) and immediately closes the connection, target-side teardown
> may start in softirq context before io_work drains the already
> buffered ICReq. In that case, nvmet_tcp_schedule_release_queue()
> sets queue->state to NVMET_TCP_Q_DISCONNECTING and drops the queue
> reference under state_lock.
>
> If io_work later processes that ICReq, nvmet_tcp_handle_icreq() can
> still overwrite the state back to NVMET_TCP_Q_LIVE. That defeats the
> DISCONNECTING-state guard in nvmet_tcp_schedule_release_queue() and
> allows a later socket state change to re-enter teardown and issue a
> second kref_put() on an already released queue.
>
> The ICResp send failure path has the same problem. If teardown has
> already moved the queue to DISCONNECTING, a send error can still
> overwrite the state with NVMET_TCP_Q_FAILED, again reopening the
> window for a second teardown path to drop the queue reference.
>
> Fix this by serializing both post-send state transitions with
> state_lock and bailing out if teardown has already started.
>
> Use -ESHUTDOWN as an internal sentinel for that bail-out path rather
> than propagating it as a transport error like -ECONNRESET. Keep
> nvmet_tcp_socket_error() setting rcv_state to NVMET_TCP_RECV_ERR before
> honoring that sentinel so receive-side parsing stays quiesced until the
> existing release path completes.
>
> Reported-by: Shivam Kumar <skumar47 at syr.edu>
> Fixes: c46a6465bac2 ("nvmet-tcp: add NVMe over TCP target driver")
> Cc: stable at vger.kernel.org
> Signed-off-by: Chaitanya Kulkarni <kch at nvidia.com>
> ---
>
> Hi Shivam,
>
> This patch is different than the one I posted.
>
> Posted patch :-
>
>
>                 iov.iov_len = sizeof(*icresp);
>                 ret = kernel_sendmsg(queue->sock, &msg, &iov, 1, iov.iov_len);
>                 if (ret < 0) {
>         -               queue->state = NVMET_TCP_Q_FAILED;
>         +               spin_lock_bh(&queue->state_lock);
>         +               if (queue->state != NVMET_TCP_Q_DISCONNECTING)
>         +                       queue->state = NVMET_TCP_Q_FAILED;
>         +               spin_unlock_bh(&queue->state_lock);
>                         return ret; /* queue removal will cleanup */
>                 }
>
> This patch :-
>
>                 iov.iov_len = sizeof(*icresp);
>                 ret = kernel_sendmsg(queue->sock, &msg, &iov, 1, iov.iov_len);
>                 if (ret < 0) {
>         +               spin_lock_bh(&queue->state_lock);
>         +               if (queue->state == NVMET_TCP_Q_DISCONNECTING) {
>         +                       spin_unlock_bh(&queue->state_lock);
>         +                       return -ESHUTDOWN;
>         +               }
>                         queue->state = NVMET_TCP_Q_FAILED;
>         +               spin_unlock_bh(&queue->state_lock);
>                         return ret; /* queue removal will cleanup */
>                 }
>
> It will be great if you can provide tested-by tag on this patch
> so we can merge this fix as well.
>
> -ck
>
> ---
>  drivers/nvme/target/tcp.c | 28 ++++++++++++++++++++++++++++
>  1 file changed, 28 insertions(+)
>
> diff --git a/drivers/nvme/target/tcp.c b/drivers/nvme/target/tcp.c
> index 69e971b179ae..98b2ce9a70ca 100644
> --- a/drivers/nvme/target/tcp.c
> +++ b/drivers/nvme/target/tcp.c
> @@ -407,7 +407,22 @@ static void nvmet_tcp_fatal_error(struct nvmet_tcp_queue *queue)
>
>  static void nvmet_tcp_socket_error(struct nvmet_tcp_queue *queue, int status)
>  {
> +       /*
> +        * Keep rcv_state at RECV_ERR even for the internal -ESHUTDOWN path.
> +        * nvmet_tcp_handle_icreq() can return -ESHUTDOWN after the ICReq has
> +        * already been consumed and queue teardown has started.
> +        *
> +        * If nvmet_tcp_data_ready() or nvmet_tcp_write_space() queues
> +        * nvmet_tcp_io_work() again before nvmet_tcp_release_queue_work()
> +        * cancels it, the queue must not keep that old receive state.
> +        * Otherwise the next nvmet_tcp_io_work() run can reach
> +        * nvmet_tcp_done_recv_pdu() and try to handle the same ICReq again.
> +        *
> +        * That is why queue->rcv_state needs to be updated before we return.
> +        */
>         queue->rcv_state = NVMET_TCP_RECV_ERR;
> +       if (status == -ESHUTDOWN)
> +               return;
>         if (status == -EPIPE || status == -ECONNRESET)
>                 kernel_sock_shutdown(queue->sock, SHUT_RDWR);
>         else
> @@ -922,11 +937,24 @@ static int nvmet_tcp_handle_icreq(struct nvmet_tcp_queue *queue)
>         iov.iov_len = sizeof(*icresp);
>         ret = kernel_sendmsg(queue->sock, &msg, &iov, 1, iov.iov_len);
>         if (ret < 0) {
> +               spin_lock_bh(&queue->state_lock);
> +               if (queue->state == NVMET_TCP_Q_DISCONNECTING) {
> +                       spin_unlock_bh(&queue->state_lock);
> +                       return -ESHUTDOWN;
> +               }
>                 queue->state = NVMET_TCP_Q_FAILED;
> +               spin_unlock_bh(&queue->state_lock);
>                 return ret; /* queue removal will cleanup */
>         }
>
> +       spin_lock_bh(&queue->state_lock);
> +       if (queue->state == NVMET_TCP_Q_DISCONNECTING) {
> +               spin_unlock_bh(&queue->state_lock);
> +               /* Tell nvmet_tcp_socket_error() teardown is already in progress. */
> +               return -ESHUTDOWN;
> +       }
>         queue->state = NVMET_TCP_Q_LIVE;
> +       spin_unlock_bh(&queue->state_lock);
>         nvmet_prepare_receive_pdu(queue);
>         return 0;
>  }
> --
> 2.39.5
>
Tested this updated patch - the handle_icreq race is fixed.
Tested-by: Shivam Kumar <kumar.shivam43666 at gmail.com>