netdev - Re: [PATCH v4 net] geneve: fix header validation in geneve[6]_xmit

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Message-ID: <ZhGg3kRHpARQAv9b@equinox>
Date: Sat, 6 Apr 2024 20:22:06 +0100
From: Phillip Potter <phil@...lpotter.co.uk>
To: Eric Dumazet <edumazet@...gle.com>
Cc: davem@...emloft.net, kuba@...nel.org, pabeni@...hat.com,
	netdev@...r.kernel.org, eric.dumazet@...il.com,
	syzbot+9ee20ec1de7b3168db09@...kaller.appspotmail.com,
	sd@...asysnail.net
Subject: Re: [PATCH v4 net] geneve: fix header validation in
 geneve[6]_xmit_skb

On Fri, Apr 05, 2024 at 10:30:34AM +0000, Eric Dumazet wrote:
> syzbot is able to trigger an uninit-value in geneve_xmit() [1]
> 
> Problem : While most ip tunnel helpers (like ip_tunnel_get_dsfield())
> uses skb_protocol(skb, true), pskb_inet_may_pull() is only using
> skb->protocol.
> 
> If anything else than ETH_P_IPV6 or ETH_P_IP is found in skb->protocol,
> pskb_inet_may_pull() does nothing at all.
> 
> If a vlan tag was provided by the caller (af_packet in the syzbot case),
> the network header might not point to the correct location, and skb
> linear part could be smaller than expected.
> 
> Add skb_vlan_inet_prepare() to perform a complete mac validation.
> 
> Use this in geneve for the moment, I suspect we need to adopt this
> more broadly.
> 
> v4 - Jakub reported v3 broke l2_tos_ttl_inherit.sh selftest
>    - Only call __vlan_get_protocol() for vlan types.
> Link: https://lore.kernel.org/netdev/20240404100035.3270a7d5@kernel.org/
> 
> v2,v3 - Addressed Sabrina comments on v1 and v2
> Link: https://lore.kernel.org/netdev/Zg1l9L2BNoZWZDZG@hog/
> 
> [1]
> 

Hi Eric,

Looks good.

Reviewed-by: Phillip Potter <phil@...lpotter.co.uk>

Regards,
Phil