6.1-stable review patch. If anyone has any objections, please let me know.
------------------
From: Eric Dumazet edumazet@google.com
[ 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@google.com Reviewed-by: Kuniyuki Iwashima kuniyu@amazon.com Link: https://patch.msgid.link/20250205155120.1676781-11-edumazet@google.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/ipv6/route.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/net/ipv6/route.c b/net/ipv6/route.c index f3268bac9f198..17918f411386a 100644 --- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -3190,13 +3190,18 @@ 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.