drm/virtio: Ensure cached capset entries are valid before copying. (7fdf478a) · Commits · 戴 / test

virtio_gpu_get_caps_ioctl could return success with invalid data if a second caller to the function occurred after the entry was created in virtio_gpu_cmd_get_capset but prior to the virtio_gpu_cmd_capset_cb callback being called. This could leak contents of memory as well since the caps_cache allocation is done without zeroing. Signed-off-by:

David Riley <davidriley@chromium.org> Link: http://patchwork.freedesktop.org/patch/msgid/20190605234423.11348-1-davidriley@chromium.org Signed-off-by:

Gerd Hoffmann <kraxel@redhat.com>

drivers/gpu/drm/virtio/virtgpu_ioctl.c

+1 −2

Original line number	Diff line number	Diff line
		@@ -524,7 +524,6 @@ static int virtio_gpu_get_caps_ioctl(struct drm_device *dev,
		list_for_each_entry(cache_ent, &vgdev->cap_cache, head) {
		if (cache_ent->id == args->cap_set_id &&
		cache_ent->version == args->cap_set_ver) {
		ptr = cache_ent->caps_cache;
		spin_unlock(&vgdev->display_info_lock);
		goto copy_exit;
		}
		@@ -535,6 +534,7 @@ static int virtio_gpu_get_caps_ioctl(struct drm_device *dev,
		virtio_gpu_cmd_get_capset(vgdev, found_valid, args->cap_set_ver,
		&cache_ent);

		copy_exit:
		ret = wait_event_timeout(vgdev->resp_wq,
		atomic_read(&cache_ent->is_valid), 5 * HZ);
		if (!ret)
		@@ -542,7 +542,6 @@ static int virtio_gpu_get_caps_ioctl(struct drm_device *dev,

		ptr = cache_ent->caps_cache;

		copy_exit:
		if (copy_to_user(u64_to_user_ptr(args->addr), ptr, size))
		return -EFAULT;

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