[PATCH] nvme-tcp: fix possible req->offset corruption
Keith Busch
kbusch at kernel.org
Tue Oct 26 07:27:39 PDT 2021
On Tue, Oct 26, 2021 at 07:01:55PM +0530, Varun Prakash wrote:
> With commit db5ad6b7f8cd ("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().
Nice catch.
Reviewed-by: Keith Busch <kbusch at kernel.org>
> Fixes: db5ad6b7f8cd ("nvme-tcp: try to send request in queue_rq context")
> Signed-off-by: Varun Prakash <varun at chelsio.com>
> ---
> drivers/nvme/host/tcp.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
> index 22da856..2217897 100644
> --- a/drivers/nvme/host/tcp.c
> +++ b/drivers/nvme/host/tcp.c
> @@ -1048,6 +1048,7 @@ 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 = {
> @@ -1064,7 +1065,7 @@ 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;
> }
> --
> 2.0.2
>
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