Hi， Thank you for your reply. In nvme-rdma we use nvme_host_path_error(rq) , the prerequisites are -EIO, ignore this condition? in nvme-tcp this judgment condition is different, use the function nvme_host_path_error , it should be possible to go to nvme_complete_rq -> nvme_retry_req -- request->mq_hctx have been freed, is NULL. zhang.guanghui@xxxxxxxx From: Max Gurtovoy Date: 2025-02-10 18:24 To: Maurizio Lombardi; zhang.guanghui@xxxxxxxx; sagi; kbusch; sashal; chunguang.xu CC: linux-kernel; linux-nvme; linux-block Subject: Re: nvme-tcp: fix a possible UAF when failing to send request On 10/02/2025 12:01, Maurizio Lombardi wrote: > On Mon Feb 10, 2025 at 8:41 AM CET, zhang.guanghui@xxxxxxxx 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 ?
