virtio_pci: add check for common cfg size

Some buggy devices, the common cfg size may not match the features.

This patch checks the common cfg size for the
features(VIRTIO_F_NOTIF_CONFIG_DATA, VIRTIO_F_RING_RESET). When the
common cfg size does not match the corresponding feature, we fail the
probe and print error message.
Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20231019034902.7346-1-xuanzhuo@linux.alibaba.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

drivers/virtio/virtio_pci_modern.c

@@ -39,6 +39,39 @@ static void vp_transport_features(struct virtio_device *vdev, u64 features)
 		__virtio_set_bit(vdev, VIRTIO_F_RING_RESET);
 }
 
+static int __vp_check_common_size_one_feature(struct virtio_device *vdev, u32 fbit,
+					    u32 offset, const char *fname)
+{
+	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+
+	if (!__virtio_test_bit(vdev, fbit))
+		return 0;
+
+	if (likely(vp_dev->mdev.common_len >= offset))
+		return 0;
+
+	dev_err(&vdev->dev,
+		"virtio: common cfg size(%zu) does not match the feature %s\n",
+		vp_dev->mdev.common_len, fname);
+
+	return -EINVAL;
+}
+
+#define vp_check_common_size_one_feature(vdev, fbit, field) \
+	__vp_check_common_size_one_feature(vdev, fbit, \
+		offsetofend(struct virtio_pci_modern_common_cfg, field), #fbit)
+
+static int vp_check_common_size(struct virtio_device *vdev)
+{
+	if (vp_check_common_size_one_feature(vdev, VIRTIO_F_NOTIF_CONFIG_DATA, queue_notify_data))
+		return -EINVAL;
+
+	if (vp_check_common_size_one_feature(vdev, VIRTIO_F_RING_RESET, queue_reset))
+		return -EINVAL;
+
+	return 0;
+}
+
 /* virtio config->finalize_features() implementation */
 static int vp_finalize_features(struct virtio_device *vdev)
 {
@@ -57,6 +90,9 @@ static int vp_finalize_features(struct virtio_device *vdev)
 		return -EINVAL;
 	}
 
+	if (vp_check_common_size(vdev))
+		return -EINVAL;
+
 	vp_modern_set_features(&vp_dev->mdev, vdev->features);
 
 	return 0;

drivers/virtio/virtio_pci_modern_dev.c

@@ -296,7 +296,7 @@ int vp_modern_probe(struct virtio_pci_modern_device *mdev)
 	mdev->common = vp_modern_map_capability(mdev, common,
 				      sizeof(struct virtio_pci_common_cfg), 4,
 				      0, sizeof(struct virtio_pci_modern_common_cfg),
-				      NULL, NULL);
+				      &mdev->common_len, NULL);
 	if (!mdev->common)
 		goto err_map_common;
 	mdev->isr = vp_modern_map_capability(mdev, isr, sizeof(u8), 1,

include/linux/virtio_pci_modern.h

@@ -45,6 +45,7 @@ struct virtio_pci_modern_device {
 
 	size_t notify_len;
 	size_t device_len;
+	size_t common_len;
 
 	int notify_map_cap;