From: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
To: Willem de Bruijn <willemdebruijn.kernel@gmail.com>,
Weiming Shi <bestswngs@gmail.com>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: willemdebruijn.kernel@gmail.com, jasowang@redhat.com,
andrew+netdev@lunn.ch, davem@davemloft.net,
edumazet@google.com, kuba@kernel.org, pabeni@redhat.com,
cong.wang@bytedance.com, stable@vger.kernel.org,
xmei5@asu.edu, Weiming Shi <bestswngs@gmail.com>
Subject: Re: [PATCH] tap: fix stack info leak in tap_ioctl() SIOCGIFHWADDR
Date: Wed, 20 May 2026 17:30:20 -0400 [thread overview]
Message-ID: <willemdebruijn.kernel.377fc4fbfbed@gmail.com> (raw)
In-Reply-To: <willemdebruijn.kernel.69dc20190163@gmail.com>
Willem de Bruijn wrote:
> Weiming Shi wrote:
> > In the SIOCGIFHWADDR path, tap_ioctl() copies 16 bytes of an
> > uninitialised on-stack struct sockaddr_storage to userspace via
> > ifr_hwaddr, but netif_get_mac_address() only writes sa_family and
> > dev->addr_len (6 for Ethernet) bytes, leaving sa_data[6..13] uninitialised.
> >
> > Those 8 trailing bytes leak kernel stack contents; SIOCGIFHWADDR on a
> > macvtap chardev returns kernel .text and direct-map pointers, defeating
> > KASLR.
> >
> > Initialise ss at declaration.
> >
> > Fixes: 3b23a32a6321 ("net: fix dev_ifsioc_locked() race condition")
> > Reported-by: Xiang Mei <xmei5@asu.edu>
> > Assisted-by: Claude:claude-opus-4-7
> > Signed-off-by: Weiming Shi <bestswngs@gmail.com>
>
> Reviewed-by: Willem de Bruijn <willemb@google.com>
But it should target [PATCH net] and
Cc: Stable@vger.kernel.org
next prev parent reply other threads:[~2026-05-20 21:30 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-20 7:57 [PATCH] tap: fix stack info leak in tap_ioctl() SIOCGIFHWADDR Weiming Shi
2026-05-20 21:22 ` Willem de Bruijn
2026-05-20 21:30 ` Willem de Bruijn [this message]
2026-05-21 15:20 ` patchwork-bot+netdevbpf
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