virtchnl: fix fake 1-elem arrays for structures allocated as `nents`

Finally, fix 3 structures which are allocated technically correctly,
i.e. the calculated size equals to the one that struct_size() would
return, except for sizeof(). For &virtchnl_vlan_filter_list_v2, use
the same approach when there are no enough space as taken previously
for &virtchnl_vlan_filter_list, i.e. let the maximum size be calculated
automatically instead of trying to guestimate it using maths.

Signed-off-by: Alexander Lobakin <[e-mail]>
Reviewed-by: Kees Cook <[e-mail]>
Tested-by: Rafal Romanowski <[e-mail]>
Signed-off-by: Tony Nguyen <[e-mail]>

drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c

···
 	struct virtchnl_rdma_qv_info *qv_info;
 	u32 v_idx, i, reg_idx, reg;
 	u32 next_q_idx, next_q_type;
+	size_t size;
 	u32 msix_vf;
 	int ret = 0;
 
···
 	}
 
 	kfree(vf->qvlist_info);
-	vf->qvlist_info = kzalloc(struct_size(vf->qvlist_info, qv_info,
-					      qvlist_info->num_vectors - 1),
-				  GFP_KERNEL);
+	size = virtchnl_struct_size(vf->qvlist_info, qv_info,
+				    qvlist_info->num_vectors);
+	vf->qvlist_info = kzalloc(size, GFP_KERNEL);
 	if (!vf->qvlist_info) {
 		ret = -ENOMEM;
 		goto err_out;

drivers/net/ethernet/intel/iavf/iavf_client.c

···
 	}
 
 	v_qvlist_info = (struct virtchnl_rdma_qvlist_info *)qvlist_info;
-	msg_size = struct_size(v_qvlist_info, qv_info,
-			       v_qvlist_info->num_vectors - 1);
+	msg_size = virtchnl_struct_size(v_qvlist_info, qv_info,
+					v_qvlist_info->num_vectors);
 
 	adapter->client_pending |= BIT(VIRTCHNL_OP_CONFIG_RDMA_IRQ_MAP);
 	err = iavf_aq_send_msg_to_pf(&adapter->hw,

drivers/net/ethernet/intel/iavf/iavf_client.h

···
 
 struct iavf_qvlist_info {
 	u32 num_vectors;
-	struct iavf_qv_info qv_info[1];
+	struct iavf_qv_info qv_info[];
 };
 
 #define IAVF_CLIENT_MSIX_ALL 0xFFFFFFFF

drivers/net/ethernet/intel/iavf/iavf_virtchnl.c

···
 			more = true;
 		}
 
-		len = sizeof(*vvfl_v2) + ((count - 1) *
-					  sizeof(struct virtchnl_vlan_filter));
+		len = virtchnl_struct_size(vvfl_v2, filters, count);
 		if (len > IAVF_MAX_AQ_BUF_SIZE) {
 			dev_warn(&adapter->pdev->dev, "Too many add VLAN changes in one request\n");
-			count = (IAVF_MAX_AQ_BUF_SIZE - sizeof(*vvfl_v2)) /
-				sizeof(struct virtchnl_vlan_filter);
-			len = sizeof(*vvfl_v2) +
-				((count - 1) *
-				 sizeof(struct virtchnl_vlan_filter));
+			while (len > IAVF_MAX_AQ_BUF_SIZE)
+				len = virtchnl_struct_size(vvfl_v2, filters,
+							   --count);
 			more = true;
 		}
 
···
 
 		adapter->current_op = VIRTCHNL_OP_DEL_VLAN_V2;
 
-		len = sizeof(*vvfl_v2) +
-			((count - 1) * sizeof(struct virtchnl_vlan_filter));
+		len = virtchnl_struct_size(vvfl_v2, filters, count);
 		if (len > IAVF_MAX_AQ_BUF_SIZE) {
 			dev_warn(&adapter->pdev->dev, "Too many add VLAN changes in one request\n");
-			count = (IAVF_MAX_AQ_BUF_SIZE -
-				 sizeof(*vvfl_v2)) /
-				sizeof(struct virtchnl_vlan_filter);
-			len = sizeof(*vvfl_v2) +
-				((count - 1) *
-				 sizeof(struct virtchnl_vlan_filter));
+			while (len > IAVF_MAX_AQ_BUF_SIZE)
+				len = virtchnl_struct_size(vvfl_v2, filters,
+							   --count);
 			more = true;
 		}
 
···
 		return;
 	}
 
-	len = struct_size(vti, list, adapter->num_tc - 1);
+	len = virtchnl_struct_size(vti, list, adapter->num_tc);
 	vti = kzalloc(len, GFP_KERNEL);
 	if (!vti)
 		return;

include/linux/avf/virtchnl.h

···
 	u16 vport_id;
 	u16 num_elements;
 	u8 pad[4];
-	struct virtchnl_vlan_filter filters[1];
+	struct virtchnl_vlan_filter filters[];
 };
 
-VIRTCHNL_CHECK_STRUCT_LEN(40, virtchnl_vlan_filter_list_v2);
+VIRTCHNL_CHECK_STRUCT_LEN(8, virtchnl_vlan_filter_list_v2);
+#define virtchnl_vlan_filter_list_v2_LEGACY_SIZEOF	40
 
 /* VIRTCHNL_OP_ENABLE_VLAN_STRIPPING_V2
  * VIRTCHNL_OP_DISABLE_VLAN_STRIPPING_V2
···
 struct virtchnl_tc_info {
 	u32	num_tc;
 	u32	pad;
-	struct	virtchnl_channel_info list[1];
+	struct virtchnl_channel_info list[];
 };
 
-VIRTCHNL_CHECK_STRUCT_LEN(24, virtchnl_tc_info);
+VIRTCHNL_CHECK_STRUCT_LEN(8, virtchnl_tc_info);
+#define virtchnl_tc_info_LEGACY_SIZEOF	24
 
 /* VIRTCHNL_ADD_CLOUD_FILTER
  * VIRTCHNL_DEL_CLOUD_FILTER
···
 
 struct virtchnl_rdma_qvlist_info {
 	u32 num_vectors;
-	struct virtchnl_rdma_qv_info qv_info[1];
+	struct virtchnl_rdma_qv_info qv_info[];
 };
 
-VIRTCHNL_CHECK_STRUCT_LEN(16, virtchnl_rdma_qvlist_info);
+VIRTCHNL_CHECK_STRUCT_LEN(4, virtchnl_rdma_qvlist_info);
+#define virtchnl_rdma_qvlist_info_LEGACY_SIZEOF	16
 
 /* VF reset states - these are written into the RSTAT register:
  * VFGEN_RSTAT on the VF
···
 #define __vss_byone(p, member, count, old)				      \
 	(struct_size(p, member, count) + (old - 1 - struct_size(p, member, 0)))
 
+#define __vss_byelem(p, member, count, old)				      \
+	(struct_size(p, member, count - 1) + (old - struct_size(p, member, 0)))
+
 #define __vss_full(p, member, count, old)				      \
 	(struct_size(p, member, count) + (old - struct_size(p, member, 0)))
 
···
 		 __vss(virtchnl_irq_map_info, __vss_full, p, m, c),	      \
 		 __vss(virtchnl_ether_addr_list, __vss_full, p, m, c),	      \
 		 __vss(virtchnl_vlan_filter_list, __vss_full, p, m, c),	      \
+		 __vss(virtchnl_vlan_filter_list_v2, __vss_byelem, p, m, c),  \
+		 __vss(virtchnl_tc_info, __vss_byelem, p, m, c),	      \
+		 __vss(virtchnl_rdma_qvlist_info, __vss_byelem, p, m, c),     \
 		 __vss(virtchnl_rss_key, __vss_byone, p, m, c),		      \
 		 __vss(virtchnl_rss_lut, __vss_byone, p, m, c))
 
···
 	case VIRTCHNL_OP_RELEASE_RDMA_IRQ_MAP:
 		break;
 	case VIRTCHNL_OP_CONFIG_RDMA_IRQ_MAP:
-		valid_len = sizeof(struct virtchnl_rdma_qvlist_info);
+		valid_len = virtchnl_rdma_qvlist_info_LEGACY_SIZEOF;
 		if (msglen >= valid_len) {
 			struct virtchnl_rdma_qvlist_info *qv =
 				(struct virtchnl_rdma_qvlist_info *)msg;
 
-			valid_len += ((qv->num_vectors - 1) *
-				sizeof(struct virtchnl_rdma_qv_info));
+			valid_len = virtchnl_struct_size(qv, qv_info,
+							 qv->num_vectors);
 		}
 		break;
 	case VIRTCHNL_OP_CONFIG_RSS_KEY:
···
 		valid_len = sizeof(struct virtchnl_vf_res_request);
 		break;
 	case VIRTCHNL_OP_ENABLE_CHANNELS:
-		valid_len = sizeof(struct virtchnl_tc_info);
+		valid_len = virtchnl_tc_info_LEGACY_SIZEOF;
 		if (msglen >= valid_len) {
 			struct virtchnl_tc_info *vti =
 				(struct virtchnl_tc_info *)msg;
-			valid_len += (vti->num_tc - 1) *
-				     sizeof(struct virtchnl_channel_info);
+			valid_len = virtchnl_struct_size(vti, list,
+							 vti->num_tc);
 			if (vti->num_tc == 0)
 				err_msg_format = true;
 		}
···
 		break;
 	case VIRTCHNL_OP_ADD_VLAN_V2:
 	case VIRTCHNL_OP_DEL_VLAN_V2:
-		valid_len = sizeof(struct virtchnl_vlan_filter_list_v2);
+		valid_len = virtchnl_vlan_filter_list_v2_LEGACY_SIZEOF;
 		if (msglen >= valid_len) {
 			struct virtchnl_vlan_filter_list_v2 *vfl =
 			    (struct virtchnl_vlan_filter_list_v2 *)msg;
 
-			valid_len += (vfl->num_elements - 1) *
-				sizeof(struct virtchnl_vlan_filter);
+			valid_len = virtchnl_struct_size(vfl, filters,
+							 vfl->num_elements);
 
 			if (vfl->num_elements == 0) {
 				err_msg_format = true;