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

[Max Gurtovoy]

On 10/02/2025 12:01, Maurizio Lombardi wrote:
> On Mon Feb 10, 2025 at 8:41 AM CET, zhang.guanghui at cestc.cn wrote:
>> Hello
>>
>>
> I guess you have to fix your mail client.
>
>>      When using the nvme-tcp driver in a storage cluster, the driver may trigger a null pointer causing the host to crash several times.
>> By analyzing the vmcore, we know the direct cause is that  the request->mq_hctx was used after free.
>>
>>
>> CPU1                                                                   CPU2
>>
>> nvme_tcp_poll                                                          nvme_tcp_try_send  --failed to send reqrest 13
> This simply looks like a race condition between nvme_tcp_poll() and nvme_tcp_try_send()
> Personally, I would try to fix it inside the nvme-tcp driver without
> touching the core functions.
>
> Maybe nvme_tcp_poll should just ensure that io_work completes before
> calling nvme_tcp_try_recv(), the POLLING flag should then prevent io_work
> from getting rescheduled by the nvme_tcp_data_ready() callback.
>
>
> Maurizio

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 ?