From: Eric Dumazet <edumazet@google.com>
Date: Wed, 5 Feb 2025 15:51:13 +0000 (+0000)
Subject: ipv4: use RCU protection in rt_is_expired()
X-Git-Tag: v6.14-rc3~37^2~28^2~7
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=dd205fcc33d92d54eee4d7f21bb073af9bd5ce2b;p=thirdparty%2Flinux.git

ipv4: use RCU protection in rt_is_expired()

rt_is_expired() must use RCU protection to make
sure the net structure it reads does not disappear.

Fixes: e84f84f27647 ("netns: place rt_genid into struct net")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250205155120.1676781-6-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---

diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 74c074f45758b..e959327c0ba89 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -390,7 +390,13 @@ static inline int ip_rt_proc_init(void)
 
 static inline bool rt_is_expired(const struct rtable *rth)
 {
-	return rth->rt_genid != rt_genid_ipv4(dev_net(rth->dst.dev));
+	bool res;
+
+	rcu_read_lock();
+	res = rth->rt_genid != rt_genid_ipv4(dev_net_rcu(rth->dst.dev));
+	rcu_read_unlock();
+
+	return res;
 }
 
 void rt_cache_flush(struct net *net)