On 12/8/25 19:02, Alexey Simakov wrote:
> According to MAX_CAPSET_ID, possible values of vgdev->capsets[i].id
> range from 0 to 63. Since the intermediate calculation uses type int,
> shifting by values larger than the bit width of int is undefined
> behavior as per the C language standard.
>
> Explicitly cast the left-shift operand to ULL to prevent undefined
> behavior during the calculation.
>
> Found by Linux Verification Center (linuxtesting.org) with Svace.
>
> Fixes: 1925d6a7e0f4 ("drm/virtio: implement context init: track valid
> capabilities in a mask")
> Signed-off-by: Alexey Simakov <[email protected]>
> ---
> drivers/gpu/drm/virtio/virtgpu_kms.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/virtio/virtgpu_kms.c
> b/drivers/gpu/drm/virtio/virtgpu_kms.c
> index 1c15cbf326b7..2e0ec7590ac2 100644
> --- a/drivers/gpu/drm/virtio/virtgpu_kms.c
> +++ b/drivers/gpu/drm/virtio/virtgpu_kms.c
> @@ -104,7 +104,7 @@ static void virtio_gpu_get_capsets(struct
> virtio_gpu_device *vgdev,
> return;
> }
>
> - vgdev->capset_id_mask |= 1 << vgdev->capsets[i].id;
> + vgdev->capset_id_mask |= 1ULL << vgdev->capsets[i].id;
> DRM_INFO("cap set %d: id %d, max-version %d, max-size %d\n",
> i, vgdev->capsets[i].id,
> vgdev->capsets[i].max_version,
Reviewed-by: Dmitry Osipenko <[email protected]>
--
Best regards,
Dmitry
