This is a note to let you know that I've just added the patch titled
ipv6: use RCU protection in ip6_default_advmss()
to the 6.13-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ipv6-use-rcu-protection-in-ip6_default_advmss.patch
and it can be found in the queue-6.13 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit d00acab98c62e79343dac4811af016a999cefc1e
Author: Eric Dumazet <edumazet@xxxxxxxxxx>
Date: Wed Feb 5 15:51:18 2025 +0000
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: 5578689a4e3c ("[NETNS][IPV6] route6 - make route6 per namespace")
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Reviewed-by: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
Link: https://patch.msgid.link/20250205155120.1676781-11-edumazet@xxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 67ff16c047180..997e2e4f441d2 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -3196,13 +3196,18 @@ 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.
