From: Paolo Abeni <pabeni@redhat.com>
Date: Thu, 21 Feb 2019 16:44:00 +0000 (+0100)
Subject: udp: fix possible user after free in error handler
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=92b95364235b6441a36861ff0ca4541a13351d60;p=linux.git

udp: fix possible user after free in error handler

Similar to the previous commit, this addresses the same issue for
ipv4: use a single fetch operation and use the correct rcu
annotation.

Fixes: e7cc082455cb ("udp: Support for error handlers of tunnels with arbitrary destination port")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Acked-by: Stefano Brivio <sbrivio@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 5c3cd5d84a6f6..372fdc5381a98 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -562,10 +562,12 @@ static int __udp4_lib_err_encap_no_sk(struct sk_buff *skb, u32 info)
 
 	for (i = 0; i < MAX_IPTUN_ENCAP_OPS; i++) {
 		int (*handler)(struct sk_buff *skb, u32 info);
+		const struct ip_tunnel_encap_ops *encap;
 
-		if (!iptun_encaps[i])
+		encap = rcu_dereference(iptun_encaps[i]);
+		if (!encap)
 			continue;
-		handler = rcu_dereference(iptun_encaps[i]->err_handler);
+		handler = encap->err_handler;
 		if (handler && !handler(skb, info))
 			return 0;
 	}