From a42b69f692165ec39db42d595f4f65a4c8f42e44 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Fri, 7 Feb 2025 13:58:36 +0000 Subject: [PATCH] arp: use RCU protection in arp_xmit() arp_xmit() can be called without RTNL or RCU protection. Use RCU protection to avoid potential UAF. Fixes: 29a26a568038 ("netfilter: Pass struct net into the netfilter hooks") Signed-off-by: Eric Dumazet Reviewed-by: David Ahern Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20250207135841.1948589-5-edumazet@google.com Signed-off-by: Jakub Kicinski --- net/ipv4/arp.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c index cb9a7ed8abd3..f23a1ec6694c 100644 --- a/net/ipv4/arp.c +++ b/net/ipv4/arp.c @@ -659,10 +659,12 @@ static int arp_xmit_finish(struct net *net, struct sock *sk, struct sk_buff *skb */ void arp_xmit(struct sk_buff *skb) { + rcu_read_lock(); /* Send it off, maybe filter it using firewalling first. */ NF_HOOK(NFPROTO_ARP, NF_ARP_OUT, - dev_net(skb->dev), NULL, skb, NULL, skb->dev, + dev_net_rcu(skb->dev), NULL, skb, NULL, skb->dev, arp_xmit_finish); + rcu_read_unlock(); } EXPORT_SYMBOL(arp_xmit);