netdev - Re: [PATCH net-next] udp: properly deal with xfrm encap and ADDRFORM

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Message-ID: <Z_eNgJBm5RucHjxb@krikkit>
Date: Thu, 10 Apr 2025 11:21:04 +0200
From: Sabrina Dubroca <sd@...asysnail.net>
To: Paolo Abeni <pabeni@...hat.com>
Cc: netdev@...r.kernel.org, "David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Simon Horman <horms@...nel.org>,
	Willem de Bruijn <willemdebruijn.kernel@...il.com>,
	David Ahern <dsahern@...nel.org>,
	Eyal Birger <eyal.birger@...il.com>,
	Steffen Klassert <steffen.klassert@...unet.com>,
	Antony Antony <antony.antony@...unet.com>
Subject: Re: [PATCH net-next] udp: properly deal with xfrm encap and ADDRFORM

2025-04-09, 22:00:56 +0200, Paolo Abeni wrote:
> UDP GRO accounting assumes that the GRO receive callback is always
> set when the UDP tunnel is enabled, but syzkaller proved otherwise,
> leading tot the following splat:
[...]
> 
> Address the issue moving the accounting hook into
> setup_udp_tunnel_sock() and set_xfrm_gro_udp_encap_rcv(), where
> the GRO callback is actually set.
> 
> set_xfrm_gro_udp_encap_rcv() is prone to races with IPV6_ADDRFORM,
> run the relevant setsockopt under the socket lock to ensure using
> consistent values of sk_family and up->encap_type.
> 
> Refactor the GRO callback selection code, to make it clear that
> the function pointer is always initialized.
> 
> Reported-by: syzbot+8c469a2260132cd095c1@...kaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?extid=8c469a2260132cd095c1
> Fixes: 172bf009c18d ("xfrm: Support GRO for IPv4 ESP in UDP encapsulation")
> Fixes: 5d7f5b2f6b935 ("udp_tunnel: use static call for GRO hooks when possible")
> Signed-off-by: Paolo Abeni <pabeni@...hat.com>

Reviewed-by: Sabrina Dubroca <sd@...asysnail.net>

-- 
Sabrina