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Subject[PATCH 3.12 027/142] l2tp: avoid use-after-free caused by l2tp_ip_backlog_recv
Date
From: Paul Hüber <phueber@kernsp.in>

3.12-stable review patch. If anyone has any objections, please let me know.

===============

[ Upstream commit 51fb60eb162ab84c5edf2ae9c63cf0b878e5547e ]

l2tp_ip_backlog_recv may not return -1 if the packet gets dropped.
The return value is passed up to ip_local_deliver_finish, which treats
negative values as an IP protocol number for resubmission.

Signed-off-by: Paul Hüber <phueber@kernsp.in>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
net/l2tp/l2tp_ip.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/l2tp/l2tp_ip.c b/net/l2tp/l2tp_ip.c
index b69b762159ad..c44b3742ae36 100644
--- a/net/l2tp/l2tp_ip.c
+++ b/net/l2tp/l2tp_ip.c
@@ -383,7 +383,7 @@ static int l2tp_ip_backlog_recv(struct sock *sk, struct sk_buff *skb)
drop:
IP_INC_STATS(sock_net(sk), IPSTATS_MIB_INDISCARDS);
kfree_skb(skb);
- return -1;
+ return 0;
}

/* Userspace will call sendmsg() on the tunnel socket to send L2TP
--
2.12.2
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