Re: [PATCH net-next net] netdev: Hide the netdev_priv() origin from GCC in netdev_from_priv()

[Qingfang Deng]

Hi,

On 10/16/2026 1:00 AM, Kees Cook wrote:
> --- a/include/linux/netdevice.h
> +++ b/include/linux/netdevice.h
> @@ -2838,6 +2838,13 @@ static inline void *netdev_priv(const struct net_device *dev)
>    */
>   static inline struct net_device *netdev_from_priv(const void *priv)
>   {
> +	/*
> +	 * When GCC can see that @priv came from netdev_priv(), it can
> +	 * compute an object size of 0 for the net_device and its members,
> +	 * which makes FORTIFY_SOURCE fail valid accesses through the result:
> +	 * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=127875
> +	 */
> +	OPTIMIZER_HIDE_VAR(priv);

If this bug only affects GCC, you may wrap it with a
#ifdef CONFIG_CC_IS_GCC block.

>   	return container_of(priv, struct net_device, priv);
>   }
>   

Kind regards,