vp_vdpa: fix id_table array not null terminated error

Allocate one extra virtio_device_id as null terminator, otherwise
vdpa_mgmtdev_get_classes() may iterate multiple times and visit
undefined memory.

Fixes: ffbda8e9df10 ("vdpa/vp_vdpa : add vdpa tool support in vp_vdpa")
Cc: [e-mail]
Suggested-by: Parav Pandit <[e-mail]>
Signed-off-by: Angus Chen <[e-mail]>
Signed-off-by: Xiaoguang Wang <[e-mail]>
Message-Id: <[e-mail]>
Signed-off-by: Michael S. Tsirkin <[e-mail]>
Reviewed-by: Parav Pandit <[e-mail]>
Acked-by: Jason Wang <[e-mail]>

drivers/vdpa/virtio_pci/vp_vdpa.c

···
 		goto mdev_err;
 	}
 
-	mdev_id = kzalloc(sizeof(struct virtio_device_id), GFP_KERNEL);
+	/*
+	 * id_table should be a null terminated array, so allocate one additional
+	 * entry here, see vdpa_mgmtdev_get_classes().
+	 */
+	mdev_id = kcalloc(2, sizeof(struct virtio_device_id), GFP_KERNEL);
 	if (!mdev_id) {
 		err = -ENOMEM;
 		goto mdev_id_err;
···
 		goto probe_err;
 	}
 
-	mdev_id->device = mdev->id.device;
-	mdev_id->vendor = mdev->id.vendor;
+	mdev_id[0].device = mdev->id.device;
+	mdev_id[0].vendor = mdev->id.vendor;
 	mgtdev->id_table = mdev_id;
 	mgtdev->max_supported_vqs = vp_modern_get_num_queues(mdev);
 	mgtdev->supported_features = vp_modern_get_features(mdev);