inet: fix IP(V6)_RECVORIGDSTADDR for udp sockets

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>

diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
index 8b13881ed0644c3c32e87718752f8613023c72eb..976073417b03cb1f3e550f897174c140bd49752b 100644 (file)
--- a/net/ipv4/ip_sockglue.c
+++ b/net/ipv4/ip_sockglue.c
@@ -148,7 +148,7 @@ 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 0489e19258adeb86e456c167c77702d8b6efee84..1407426bc862dca082bce07d037d9da3304b1715 100644 (file)
--- a/net/ipv6/datagram.c
+++ b/net/ipv6/datagram.c
@@ -701,7 +701,7 @@ 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.