Commit e219688f authored by Doug Horn's avatar Doug Horn Committed by Gerd Hoffmann
Browse files

Fix use after free in get_capset_info callback. 



If a response to virtio_gpu_cmd_get_capset_info takes longer than
five seconds to return, the callback will access freed kernel memory
in vg->capsets.

Signed-off-by: default avatarDoug Horn <doughorn@google.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20200902210847.2689-2-gurchetansingh@chromium.org


Signed-off-by: default avatarGerd Hoffmann <kraxel@redhat.com>
parent 707d561f

drivers/gpu/drm/virtio/virtgpu_kms.c

+2 −0
Original line number Diff line number Diff line
@@ -80,8 +80,10 @@ static void virtio_gpu_get_capsets(struct virtio_gpu_device *vgdev, 
					 vgdev->capsets[i].id > 0, 5 * HZ);

		if (ret == 0) {

			DRM_ERROR("timed out waiting for cap set %d\n", i);

			spin_lock(&vgdev->display_info_lock);

			kfree(vgdev->capsets);

			vgdev->capsets = NULL;

			spin_unlock(&vgdev->display_info_lock);

			return;

		}

		DRM_INFO("cap set %d: id %d, max-version %d, max-size %d\n",

drivers/gpu/drm/virtio/virtgpu_vq.c

+7 −3
Original line number Diff line number Diff line
@@ -684,9 +684,13 @@ static void virtio_gpu_cmd_get_capset_info_cb(struct virtio_gpu_device *vgdev, 
	int i = le32_to_cpu(cmd->capset_index);



	spin_lock(&vgdev->display_info_lock);

	if (vgdev->capsets) {

		vgdev->capsets[i].id = le32_to_cpu(resp->capset_id);

		vgdev->capsets[i].max_version = le32_to_cpu(resp->capset_max_version);

		vgdev->capsets[i].max_size = le32_to_cpu(resp->capset_max_size);

	} else {

		DRM_ERROR("invalid capset memory.");

	}

	spin_unlock(&vgdev->display_info_lock);

	wake_up(&vgdev->resp_wq);

}

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