| From | Ben Hutchings <> | Date | Thu, 28 Dec 2017 17:05:44 +0000 | Subject | [PATCH 3.16 168/204] l2tp: hold tunnel socket when handling control frames in l2tp_ip and l2tp_ip6 |
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3.16.52-rc1 review patch. If anyone has any objections, please let me know.
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From: Guillaume Nault <g.nault@alphalink.fr>
commit 94d7ee0baa8b764cf64ad91ed69464c1a6a0066b upstream.
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 <g.nault@alphalink.fr> Signed-off-by: David S. Miller <davem@davemloft.net> [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> --- net/l2tp/l2tp_ip.c | 5 +++-- net/l2tp/l2tp_ip6.c | 5 +++-- 2 files changed, 6 insertions(+), 4 deletions(-)
--- 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); --- a/net/l2tp/l2tp_ip6.c +++ b/net/l2tp/l2tp_ip6.c @@ -190,9 +190,10 @@ pass_up: tunnel_id = ntohl(*(__be32 *) &skb->data[4]); tunnel = l2tp_tunnel_find(&init_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);
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