From: Jakub Kicinski <kuba@kernel.org>
To: Yizhou Zhao <zhaoyz24@mails.tsinghua.edu.cn>
Cc: netdev@vger.kernel.org, "David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Paolo Abeni <pabeni@redhat.com>, Simon Horman <horms@kernel.org>,
linux-kernel@vger.kernel.org, stable@vger.kernel.org,
Yuxiang Yang <yangyx22@mails.tsinghua.edu.cn>,
Ao Wang <wangao@seu.edu.cn>, Xuewei Feng <fengxw06@126.com>,
Qi Li <qli01@tsinghua.edu.cn>, Ke Xu <xuke@tsinghua.edu.cn>
Subject: Re: [PATCH net] fddi: validate skb length before parsing headers
Date: Wed, 10 Jun 2026 08:14:48 -0700 [thread overview]
Message-ID: <20260610081448.3a963be9@kernel.org> (raw)
In-Reply-To: <20260607112408.92988-1-zhaoyz24@mails.tsinghua.edu.cn>
On Sun, 7 Jun 2026 19:24:04 +0800 Yizhou Zhao wrote:
> KASAN reports this when such a frame is processed through a dummy FDDI
> netdev that calls the real fddi_type_trans() on an exact kmalloc() copy
> of the frame:
>
> BUG: KASAN: slab-out-of-bounds in fddi_type_trans+0x385/0x3a0
> Read of size 2 at addr ffff888009c6fe33
> The buggy address is located 4 bytes to the right of
> allocated 15-byte region [ffff888009c6fe20, ffff888009c6fe2f)
>
> Reject short frames before reading the fields: require the minimum 802.2
> header length before accessing dsap or daddr, and require the full SNAP
> header length before reading the SNAP ethertype. Returning protocol 0
> causes the malformed packet to be ignored by protocol handlers.
>
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Cc: stable@vger.kernel.org
I'm stripping these, the problem seems entirely theoretical.
"I invented a fake driver and it makes the stack crash" is not serious.
next prev parent reply other threads:[~2026-06-10 15:14 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-07 11:24 [PATCH net] fddi: validate skb length before parsing headers Yizhou Zhao
2026-06-10 14:24 ` Simon Horman
2026-06-10 15:14 ` Jakub Kicinski [this message]
2026-06-10 15:20 ` patchwork-bot+netdevbpf
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