Re: [PATCH 3/4] drm/panthor: Reset the FW VM to NULL on unplug

[Steven Price <steven.price@xxxxxxx>]

On 02/05/2024 19:38, Boris Brezillon wrote:
> This way get NULL derefs instead of use-after-free if the FW VM is
> referenced after the device has been unplugged.
> 
> Signed-off-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx>

Reviewed-by: Steven Price <steven.price@xxxxxxx>

> ---
>  drivers/gpu/drm/panthor/panthor_fw.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/gpu/drm/panthor/panthor_fw.c b/drivers/gpu/drm/panthor/panthor_fw.c
> index b41685304a83..93165961a6b5 100644
> --- a/drivers/gpu/drm/panthor/panthor_fw.c
> +++ b/drivers/gpu/drm/panthor/panthor_fw.c
> @@ -1141,6 +1141,7 @@ void panthor_fw_unplug(struct panthor_device *ptdev)
>  	 * state to keep the active_refcnt balanced.
>  	 */
>  	panthor_vm_put(ptdev->fw->vm);
> +	ptdev->fw->vm = NULL;
>  
>  	panthor_gpu_power_off(ptdev, L2, ptdev->gpu_info.l2_present, 20000);
>  }