From: Qingfang Deng <qingfang.deng@linux.dev>
To: Kees Cook <kees@kernel.org>, Jakub Kicinski <kuba@kernel.org>
Cc: Andrew Lunn <andrew+netdev@lunn.ch>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Paolo Abeni <pabeni@redhat.com>, Simon Horman <horms@kernel.org>,
"Gustavo A. R. Silva" <gustavoars@kernel.org>,
Jiri Pirko <jiri@resnulli.us>,
Brad Spengler <spender@grsecurity.net>,
PaX Team <pageexec@gmail.com>, Bill Wendling <morbo@google.com>,
Justin Stitt <justinstitt@google.com>,
netdev@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
linux-hardening@vger.kernel.org,
Yeswanth Krishna Tellakula <yeswanth@linux.ibm.com>,
stable@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH net-next net] netdev: Hide the netdev_priv() origin from GCC in netdev_from_priv()
Date: Fri, 16 Oct 2026 23:19:02 +0800 [thread overview]
Message-ID: <6d16da53-0917-45cb-a5eb-5b85de5e2fb1@linux.dev> (raw)
In-Reply-To: <20261015165959.i.798-kees@kernel.org>
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,
prev parent reply other threads:[~2026-10-16 15:19 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-15 17:00 [PATCH net-next net] netdev: Hide the netdev_priv() origin from GCC in netdev_from_priv() Kees Cook
2026-10-15 17:07 ` Kees Cook
2026-10-15 17:34 ` Jakub Kicinski
2026-10-15 17:58 ` Kees Cook
2026-10-16 15:19 ` Qingfang Deng [this message]
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