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Commit 78ad0574 authored by Eric Dumazet's avatar Eric Dumazet Committed by Greg Kroah-Hartman
Browse files

ipv6: use RCU protection in ip6_default_advmss() 



[ Upstream commit 3c8ffcd248da34fc41e52a46e51505900115fc2a ]

ip6_default_advmss() needs rcu protection to make
sure the net structure it reads does not disappear.

Fixes: 5578689a ("[NETNS][IPV6] route6 - make route6 per namespace")
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Reviewed-by: default avatarKuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250205155120.1676781-11-edumazet@google.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 8cc8e128

net/ipv6/route.c

+6 −1
Original line number Diff line number Diff line
@@ -3090,13 +3090,18 @@ static unsigned int ip6_default_advmss(const struct dst_entry *dst) 
{

	struct net_device *dev = dst->dev;

	unsigned int mtu = dst_mtu(dst);

	struct net *net = dev_net(dev);

	struct net *net;



	mtu -= sizeof(struct ipv6hdr) + sizeof(struct tcphdr);



	rcu_read_lock();



	net = dev_net_rcu(dev);

	if (mtu < net->ipv6.sysctl.ip6_rt_min_advmss)

		mtu = net->ipv6.sysctl.ip6_rt_min_advmss;



	rcu_read_unlock();



	/*

	 * Maximal non-jumbo IPv6 payload is IPV6_MAXPLEN and

	 * corresponding MSS is IPV6_MAXPLEN - tcp_header_size.