From 94d7ee0baa8b764cf64ad91ed69464c1a6a0066b Mon Sep 17 00:00:00 2001 From: Guillaume Nault Date: Wed, 29 Mar 2017 08:44:59 +0200 Subject: [PATCH] l2tp: hold tunnel socket when handling control frames in l2tp_ip and l2tp_ip6 The code following l2tp_tunnel_find() expects that a new reference is held on sk. Either sk_receive_skb() or the discard_put error path will drop a reference from the tunnel's socket. This issue exists in both l2tp_ip and l2tp_ip6. Fixes: a3c18422a4b4 ("l2tp: hold socket before dropping lock in l2tp_ip{, 6}_recv()") Signed-off-by: Guillaume Nault Signed-off-by: David S. Miller --- net/l2tp/l2tp_ip.c | 5 +++-- net/l2tp/l2tp_ip6.c | 5 +++-- 2 files changed, 6 insertions(+), 4 deletions(-) diff --git a/net/l2tp/l2tp_ip.c b/net/l2tp/l2tp_ip.c index d25038cfd64e..7208fbe5856b 100644 --- a/net/l2tp/l2tp_ip.c +++ b/net/l2tp/l2tp_ip.c @@ -178,9 +178,10 @@ pass_up: tunnel_id = ntohl(*(__be32 *) &skb->data[4]); tunnel = l2tp_tunnel_find(net, tunnel_id); - if (tunnel != NULL) + if (tunnel) { sk = tunnel->sock; - else { + sock_hold(sk); + } else { struct iphdr *iph = (struct iphdr *) skb_network_header(skb); read_lock_bh(&l2tp_ip_lock); diff --git a/net/l2tp/l2tp_ip6.c b/net/l2tp/l2tp_ip6.c index a4abcbc4c09a..516d7ce24ba7 100644 --- a/net/l2tp/l2tp_ip6.c +++ b/net/l2tp/l2tp_ip6.c @@ -191,9 +191,10 @@ pass_up: tunnel_id = ntohl(*(__be32 *) &skb->data[4]); tunnel = l2tp_tunnel_find(net, tunnel_id); - if (tunnel != NULL) + if (tunnel) { sk = tunnel->sock; - else { + sock_hold(sk); + } else { struct ipv6hdr *iph = ipv6_hdr(skb); read_lock_bh(&l2tp_ip6_lock);