RDMA/mlx5: Fix udata response upon SRQ creation

Fix udata response upon SRQ creation to use the UAPI structure (i.e.
mlx5_ib_create_srq_resp). It did not zero the reserved field in userspace.

Fixes: e126ba97 ("mlx5: Add driver for Mellanox Connect-IB adapters")
Link: https://lore.kernel.org/r/20200406173540.1466477-1-leon@kernel.orgSigned-off-by: Yishai Hadas <yishaih@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/hw/mlx5/srq.c

@@ -310,12 +310,18 @@ int mlx5_ib_create_srq(struct ib_srq *ib_srq,
 	srq->msrq.event = mlx5_ib_srq_event;
 	srq->ibsrq.ext.xrc.srq_num = srq->msrq.srqn;
 
-	if (udata)
-		if (ib_copy_to_udata(udata, &srq->msrq.srqn, sizeof(__u32))) {
+	if (udata) {
+		struct mlx5_ib_create_srq_resp resp = {
+			.srqn = srq->msrq.srqn,
+		};
+
+		if (ib_copy_to_udata(udata, &resp, min(udata->outlen,
+				     sizeof(resp)))) {
 			mlx5_ib_dbg(dev, "copy to user failed\n");
 			err = -EFAULT;
 			goto err_core;
 		}
+	}
 
 	init_attr->attr.max_wr = srq->msrq.max - 1;