This is a note to let you know that I've just added the patch titled
ipv4: add RCU protection to ip4_dst_hoplimit()
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:
ipv4-add-rcu-protection-to-ip4_dst_hoplimit.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 219ce0f7b59df344e9491f142db2b216c232cb16
Author: Eric Dumazet <edumazet@xxxxxxxxxx>
Date: Wed Feb 5 15:51:10 2025 +0000
ipv4: add RCU protection to ip4_dst_hoplimit()
[ Upstream commit 469308552ca4560176cfc100e7ca84add1bebd7c ]
ip4_dst_hoplimit() must use RCU protection to make
sure the net structure it reads does not disappear.
Fixes: fa50d974d104 ("ipv4: Namespaceify ip_default_ttl sysctl knob")
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Reviewed-by: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
Link: https://patch.msgid.link/20250205155120.1676781-3-edumazet@xxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/include/net/route.h b/include/net/route.h
index 84cb1e04f5cd9..64949854d35dc 100644
--- a/include/net/route.h
+++ b/include/net/route.h
@@ -368,10 +368,15 @@ static inline int inet_iif(const struct sk_buff *skb)
static inline int ip4_dst_hoplimit(const struct dst_entry *dst)
{
int hoplimit = dst_metric_raw(dst, RTAX_HOPLIMIT);
- struct net *net = dev_net(dst->dev);
- if (hoplimit == 0)
+ if (hoplimit == 0) {
+ const struct net *net;
+
+ rcu_read_lock();
+ net = dev_net_rcu(dst->dev);
hoplimit = READ_ONCE(net->ipv4.sysctl_ip_default_ttl);
+ rcu_read_unlock();
+ }
return hoplimit;
}
