inet: fix IP(V6)_RECVORIGDSTADDR for udp sockets

[ Upstream commit 39b2dd765e0711e1efd1d1df089473a8dd93ad48 ]

Socket cmsg IP(V6)_RECVORIGDSTADDR checks that port range lies within
the packet. For sockets that have transport headers pulled, transport
offset can be negative. Use signed comparison to avoid overflow.

Fixes: e6afc8ace6dd ("udp: remove headers from UDP packets before queueing")
Reported-by: Nisar Jagabar <njagabar@cloudmark.com>
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
index b8a2d63d1fb82f5084a0d98911b8110816dee963..e869773e39794bbb40780040aea2e2483d8587f4 100644 (file)
--- a/net/ipv4/ip_sockglue.c
+++ b/net/ipv4/ip_sockglue.c
@@ -137,7 +137,7 @@ static void ip_cmsg_recv_dstaddr(struct msghdr *msg, struct sk_buff *skb)
        const struct iphdr *iph = ip_hdr(skb);
        __be16 *ports = (__be16 *)skb_transport_header(skb);
 
-       if (skb_transport_offset(skb) + 4 > skb->len)
+       if (skb_transport_offset(skb) + 4 > (int)skb->len)
                return;
 
        /* All current transport protocols have the port numbers in the

diff --git a/net/ipv6/datagram.c b/net/ipv6/datagram.c
index ccf40550c475d31bcbc0565daa4a81428e5c9c58..8616d17cf08fdda63766014ea2c4705a257bb204 100644 (file)
--- a/net/ipv6/datagram.c
+++ b/net/ipv6/datagram.c
@@ -700,7 +700,7 @@ void ip6_datagram_recv_specific_ctl(struct sock *sk, struct msghdr *msg,
                struct sockaddr_in6 sin6;
                __be16 *ports = (__be16 *) skb_transport_header(skb);
 
-               if (skb_transport_offset(skb) + 4 <= skb->len) {
+               if (skb_transport_offset(skb) + 4 <= (int)skb->len) {
                        /* All current transport protocols have the port numbers in the
                         * first four bytes of the transport header and this function is
                         * written with this assumption in mind.