udplite: call proper backlog handlers

BugLink: https://bugs.launchpad.net/bugs/1822271

commit 30c7be26 upstream.

In commits 93821778 ("udp: Fix rcv socket locking") and
f7ad74fe ("net/ipv6/udp: UDP encapsulation: break backlog_rcv into
__udpv6_queue_rcv_skb") UDP backlog handlers were renamed, but UDPlite
was forgotten.

This leads to crashes if UDPlite header is pulled twice, which happens
starting from commit e6afc8ac ("udp: remove headers from UDP packets
before queueing")

Bug found by syzkaller team, thanks a lot guys !

Note that backlog use in UDP/UDPlite is scheduled to be removed starting
from linux-4.10, so this patch is only needed up to linux-4.9

Fixes: 93821778 ("udp: Fix rcv socket locking")
Fixes: f7ad74fe ("net/ipv6/udp: UDP encapsulation: break backlog_rcv into __udpv6_queue_rcv_skb")
Fixes: e6afc8ac ("udp: remove headers from UDP packets before queueing")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Andrey Konovalov <andreyknvl@google.com>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Cc: Zubin Mithra <zsm@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: Juerg Haefliger <juerg.haefliger@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

net/ipv4/udp.c

@@ -1464,7 +1464,7 @@ static void udp_v4_rehash(struct sock *sk)
 	udp_lib_rehash(sk, new_hash);
 }
 
-static int __udp_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
+int __udp_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
 {
 	int rc;
 

net/ipv4/udp_impl.h

@@ -25,7 +25,7 @@ int udp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int noblock,
 		int flags, int *addr_len);
 int udp_sendpage(struct sock *sk, struct page *page, int offset, size_t size,
 		 int flags);
-int udp_queue_rcv_skb(struct sock *sk, struct sk_buff *skb);
+int __udp_queue_rcv_skb(struct sock *sk, struct sk_buff *skb);
 void udp_destroy_sock(struct sock *sk);
 
 #ifdef CONFIG_PROC_FS

net/ipv4/udplite.c

@@ -50,7 +50,7 @@ struct proto 	udplite_prot = {
 	.sendmsg	   = udp_sendmsg,
 	.recvmsg	   = udp_recvmsg,
 	.sendpage	   = udp_sendpage,
-	.backlog_rcv	   = udp_queue_rcv_skb,
+	.backlog_rcv	   = __udp_queue_rcv_skb,
 	.hash		   = udp_lib_hash,
 	.unhash		   = udp_lib_unhash,
 	.get_port	   = udp_v4_get_port,

net/ipv6/udp.c

@@ -585,7 +585,7 @@ void __udp6_lib_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
 	sock_put(sk);
 }
 
-static int __udpv6_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
+int __udpv6_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
 {
 	int rc;
 

net/ipv6/udp_impl.h

@@ -26,7 +26,7 @@ int compat_udpv6_getsockopt(struct sock *sk, int level, int optname,
 int udpv6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len);
 int udpv6_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int noblock,
 		  int flags, int *addr_len);
-int udpv6_queue_rcv_skb(struct sock *sk, struct sk_buff *skb);
+int __udpv6_queue_rcv_skb(struct sock *sk, struct sk_buff *skb);
 void udpv6_destroy_sock(struct sock *sk);
 
 void udp_v6_clear_sk(struct sock *sk, int size);

net/ipv6/udplite.c

@@ -45,7 +45,7 @@ struct proto udplitev6_prot = {
 	.getsockopt	   = udpv6_getsockopt,
 	.sendmsg	   = udpv6_sendmsg,
 	.recvmsg	   = udpv6_recvmsg,
-	.backlog_rcv	   = udpv6_queue_rcv_skb,
+	.backlog_rcv	   = __udpv6_queue_rcv_skb,
 	.hash		   = udp_lib_hash,
 	.unhash		   = udp_lib_unhash,
 	.get_port	   = udp_v6_get_port,