nvme-tcp: fix a possible UAF when failing to send request

[Maurizio Lombardi]

On Mon Feb 10, 2025 at 11:24 AM CET, Max Gurtovoy wrote:
>
> It seems to me that the HOST_PATH_ERROR handling can be improved in 
> nvme-tcp.
>
> In nvme-rdma we use nvme_host_path_error(rq) and nvme_cleanup_cmd(rq) in 
> case we fail to submit a command..
>
> can you try to replacing nvme_tcp_end_request(blk_mq_rq_from_pdu(req), 
> NVME_SC_HOST_PATH_ERROR); call with the similar logic we use in 
> nvme-rdma for host path error handling ?

Yes, I could try to prepare a patch.

In any case, I think the main issue here is that nvme_tcp_poll()
should be prevented from racing against io_work... and I also think
there is a possible race condition if nvme_tcp_poll() races against
the controller resetting code.

Maurizio