netdev - Re: [PATCH net] ip: validate header length on virtual device xmit

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Date:   Tue, 01 Jan 2019 12:10:18 -0800 (PST)
From:   David Miller <davem@...emloft.net>
To:     willemdebruijn.kernel@...il.com
Cc:     netdev@...r.kernel.org, edumazet@...gle.com, pabeni@...hat.com,
        xiyou.wangcong@...il.com, willemb@...gle.com,
        syzkaller@...glegroups.com
Subject: Re: [PATCH net] ip: validate header length on virtual device xmit

From: Willem de Bruijn <willemdebruijn.kernel@...il.com>
Date: Sun, 30 Dec 2018 17:24:36 -0500

> From: Willem de Bruijn <willemb@...gle.com>
> 
> KMSAN detected read beyond end of buffer in vti and sit devices when
> passing truncated packets with PF_PACKET. The issue affects additional
> ip tunnel devices.
> 
> Extend commit 76c0ddd8c3a6 ("ip6_tunnel: be careful when accessing the
> inner header") and commit ccfec9e5cb2d ("ip_tunnel: be careful when
> accessing the inner header").
> 
> Move the check to a separate helper and call at the start of each
> ndo_start_xmit function in net/ipv4 and net/ipv6.
> 
> Minor changes:
> - convert dev_kfree_skb to kfree_skb on error path,
>   as dev_kfree_skb calls consume_skb which is not for error paths.
> - use pskb_network_may_pull even though that is pedantic here,
>   as the same as pskb_may_pull for devices without llheaders.
> - do not cache ipv6 hdrs if used only once
>   (unsafe across pskb_may_pull, was more relevant to earlier patch)
> 
> Reported-by: syzbot <syzkaller@...glegroups.com>
> Signed-off-by: Willem de Bruijn <willemb@...gle.com>

Applied and queued up for -stable, thanks Willem.