From: Eric Dumazet <edumazet@google.com>
Date: Fri, 10 Feb 2017 00:15:52 +0000 (-0800)
Subject: l2tp: do not use udp_ioctl()
X-Git-Tag: v4.9.11~7
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=5b1bb4cbd7ec562d1964d37d642ca836f2b83a2c;p=thirdparty%2Fkernel%2Fstable.git

l2tp: do not use udp_ioctl()

[ Upstream commit 72fb96e7bdbbdd4421b0726992496531060f3636 ]

udp_ioctl(), as its name suggests, is used by UDP protocols,
but is also used by L2TP :(

L2TP should use its own handler, because it really does not
look the same.

SIOCINQ for instance should not assume UDP checksum or headers.

Thanks to Andrey and syzkaller team for providing the report
and a nice reproducer.

While crashes only happen on recent kernels (after commit
7c13f97ffde6 ("udp: do fwd memory scheduling on dequeue")), this
probably needs to be backported to older kernels.

Fixes: 7c13f97ffde6 ("udp: do fwd memory scheduling on dequeue")
Fixes: 85584672012e ("udp: Fix udp_poll() and ioctl()")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Andrey Konovalov <andreyknvl@google.com>
Acked-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/net/l2tp/l2tp_core.h b/net/l2tp/l2tp_core.h
index 2599af6378e40..181e755c2fc45 100644
--- a/net/l2tp/l2tp_core.h
+++ b/net/l2tp/l2tp_core.h
@@ -273,6 +273,7 @@ int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb,
 int l2tp_nl_register_ops(enum l2tp_pwtype pw_type,
 			 const struct l2tp_nl_cmd_ops *ops);
 void l2tp_nl_unregister_ops(enum l2tp_pwtype pw_type);
+int l2tp_ioctl(struct sock *sk, int cmd, unsigned long arg);
 
 /* Session reference counts. Incremented when code obtains a reference
  * to a session.
diff --git a/net/l2tp/l2tp_ip.c b/net/l2tp/l2tp_ip.c
index 8938b6ba57a03..c0f0750639bdf 100644
--- a/net/l2tp/l2tp_ip.c
+++ b/net/l2tp/l2tp_ip.c
@@ -11,6 +11,7 @@
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
+#include <asm/ioctls.h>
 #include <linux/icmp.h>
 #include <linux/module.h>
 #include <linux/skbuff.h>
@@ -560,6 +561,30 @@ out:
 	return err ? err : copied;
 }
 
+int l2tp_ioctl(struct sock *sk, int cmd, unsigned long arg)
+{
+	struct sk_buff *skb;
+	int amount;
+
+	switch (cmd) {
+	case SIOCOUTQ:
+		amount = sk_wmem_alloc_get(sk);
+		break;
+	case SIOCINQ:
+		spin_lock_bh(&sk->sk_receive_queue.lock);
+		skb = skb_peek(&sk->sk_receive_queue);
+		amount = skb ? skb->len : 0;
+		spin_unlock_bh(&sk->sk_receive_queue.lock);
+		break;
+
+	default:
+		return -ENOIOCTLCMD;
+	}
+
+	return put_user(amount, (int __user *)arg);
+}
+EXPORT_SYMBOL(l2tp_ioctl);
+
 static struct proto l2tp_ip_prot = {
 	.name		   = "L2TP/IP",
 	.owner		   = THIS_MODULE,
@@ -568,7 +593,7 @@ static struct proto l2tp_ip_prot = {
 	.bind		   = l2tp_ip_bind,
 	.connect	   = l2tp_ip_connect,
 	.disconnect	   = l2tp_ip_disconnect,
-	.ioctl		   = udp_ioctl,
+	.ioctl		   = l2tp_ioctl,
 	.destroy	   = l2tp_ip_destroy_sock,
 	.setsockopt	   = ip_setsockopt,
 	.getsockopt	   = ip_getsockopt,
diff --git a/net/l2tp/l2tp_ip6.c b/net/l2tp/l2tp_ip6.c
index aa821cb639e54..1a65c9a517b6a 100644
--- a/net/l2tp/l2tp_ip6.c
+++ b/net/l2tp/l2tp_ip6.c
@@ -729,7 +729,7 @@ static struct proto l2tp_ip6_prot = {
 	.bind		   = l2tp_ip6_bind,
 	.connect	   = l2tp_ip6_connect,
 	.disconnect	   = l2tp_ip6_disconnect,
-	.ioctl		   = udp_ioctl,
+	.ioctl		   = l2tp_ioctl,
 	.destroy	   = l2tp_ip6_destroy_sock,
 	.setsockopt	   = ipv6_setsockopt,
 	.getsockopt	   = ipv6_getsockopt,