Re: [PATCH] RDMA/rxe: Fix responder length checking for UD request packets

[Zhu Yanjun <yanjun.zhu@linux.dev>]

On 23.05.24 11:46, Honggang LI wrote:
> According to the IBA specification:
> If a UD request packet is detected with an invalid length, the request
> shall be an invalid request and it shall be silently dropped by
> the responder. The responder then waits for a new request packet.
>
> commit 689c5421bfe0 ("RDMA/rxe: Fix incorrect responder length checking")
> defers responder length check for UD QPs in function `copy_data`.
> But it introduces a regression issue for UD QPs.
>
> When the packet size is too large to fit in the receive buffer.
> `copy_data` will return error code -EINVAL. Then `send_data_in`
> will return RESPST_ERR_MALFORMED_WQE. UD QP will transfer into
> ERROR state.
>
> Fixes: 689c5421bfe0 ("RDMA/rxe: Fix incorrect responder length checking")
> Signed-off-by: Honggang LI <honggangli@163.com>
> ---
>   drivers/infiniband/sw/rxe/rxe_resp.c | 12 ++++++++++++
>   1 file changed, 12 insertions(+)
>
> diff --git a/drivers/infiniband/sw/rxe/rxe_resp.c b/drivers/infiniband/sw/rxe/rxe_resp.c
> index 963382f625d7..a74f29dcfdc9 100644
> --- a/drivers/infiniband/sw/rxe/rxe_resp.c
> +++ b/drivers/infiniband/sw/rxe/rxe_resp.c
> @@ -354,6 +354,18 @@ static enum resp_states rxe_resp_check_length(struct rxe_qp *qp,
>   	 * receive buffer later. For rmda operations additional
>   	 * length checks are performed in check_rkey.
>   	 */
> +	if ((qp_type(qp) == IB_QPT_GSI) || (qp_type(qp) == IB_QPT_UD)) {

 From IBA specification:

"

QP1, used for the General Services Interface (GSI).
•This QP uses the Unreliable Datagram transport service.
•All traffic to and from this QP uses any VL other than VL15.
•GSI packets arriving before the current packet’s command completes may 
be dropped (i.e. the minimum queue depth of QP1 is one).

"

GSI should be MAD packets. And it should have a fixed format. Not sure 
if the payload of GSI packets will exceed the size of the recv buffer.

Except the above, I am fine with this commit. Please Jason and Leon also 
comment on it.

Reviewed-by: Zhu Yanjun <yanjun.zhu@linux.dev>

Thanks,

Zhu Yanjun

> +		unsigned int recv_buffer_len = 0;
> +		unsigned int payload = payload_size(pkt);
> +
> +		for (int i = 0; i < qp->resp.wqe->dma.num_sge; i++)
> +			recv_buffer_len += qp->resp.wqe->dma.sge[i].length;
> +		if (payload + 40 > recv_buffer_len) {
> +			rxe_dbg_qp(qp, "The receive buffer is too small for this UD packet.\n");
> +			return RESPST_ERR_LENGTH;
> +		}
> +	}
> +
>   	if (pkt->mask & RXE_PAYLOAD_MASK && ((qp_type(qp) == IB_QPT_RC) ||
>   					     (qp_type(qp) == IB_QPT_UC))) {
>   		unsigned int mtu = qp->mtu;

-- 
Best Regards,
Yanjun.Zhu