Commit ce7723e9 authored by Varun Prakash's avatar Varun Prakash Committed by Christoph Hellwig
Browse files

nvme-tcp: fix possible req->offset corruption 



With commit db5ad6b7 ("nvme-tcp: try to send request in queue_rq
context") r2t and response PDU can get processed while send function
is executing.

Current data digest send code uses req->offset after kernel_sendmsg(),
this creates a race condition where req->offset gets reset before it
is used in send function.

This can happen in two cases -
1. Target sends r2t PDU which resets req->offset.
2. Target send response PDU which completes the req and then req is
   used for a new command, nvme_tcp_setup_cmd_pdu() resets req->offset.

Fix this by storing req->offset in a local variable and using
this local variable after kernel_sendmsg().

Fixes: db5ad6b7 ("nvme-tcp: try to send request in queue_rq context")
Signed-off-by: default avatarVarun Prakash <varun@chelsio.com>
Reviewed-by: default avatarKeith Busch <kbusch@kernel.org>
Reviewed-by: default avatarSagi Grimberg <sagi@grimberg.me>
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
parent 25e1f67e

drivers/nvme/host/tcp.c

+2 −1
Original line number Diff line number Diff line
@@ -1050,6 +1050,7 @@ static int nvme_tcp_try_send_data_pdu(struct nvme_tcp_request *req) 
static int nvme_tcp_try_send_ddgst(struct nvme_tcp_request *req)

{

	struct nvme_tcp_queue *queue = req->queue;

	size_t offset = req->offset;

	int ret;

	struct msghdr msg = { .msg_flags = MSG_DONTWAIT };

	struct kvec iov = {
@@ -1066,7 +1067,7 @@ static int nvme_tcp_try_send_ddgst(struct nvme_tcp_request *req) 
	if (unlikely(ret <= 0))

		return ret;



	if (req->offset + ret == NVME_TCP_DIGEST_LENGTH) {

	if (offset + ret == NVME_TCP_DIGEST_LENGTH) {

		nvme_tcp_done_send_req(queue);

		return 1;

	}