diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 3a835578fd1c..c3b20c5afa3e 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -2027,7 +2027,7 @@ err_exit:
  *	Manual configuration of address on an interface
  */
 static int inet6_addr_add(struct net *net, int ifindex, struct in6_addr *pfx,
-			  int plen, __u8 ifa_flags, __u32 prefered_lft,
+			  unsigned int plen, __u8 ifa_flags, __u32 prefered_lft,
 			  __u32 valid_lft)
 {
 	struct inet6_ifaddr *ifp;
@@ -2039,6 +2039,9 @@ static int inet6_addr_add(struct net *net, int ifindex, struct in6_addr *pfx,
 
 	ASSERT_RTNL();
 
+	if (plen > 128)
+		return -EINVAL;
+
 	/* check the lifetime */
 	if (!valid_lft || prefered_lft > valid_lft)
 		return -EINVAL;
@@ -2095,12 +2098,15 @@ static int inet6_addr_add(struct net *net, int ifindex, struct in6_addr *pfx,
 }
 
 static int inet6_addr_del(struct net *net, int ifindex, struct in6_addr *pfx,
-			  int plen)
+			  unsigned int plen)
 {
 	struct inet6_ifaddr *ifp;
 	struct inet6_dev *idev;
 	struct net_device *dev;
 
+	if (plen > 128)
+		return -EINVAL;
+
 	dev = __dev_get_by_index(net, ifindex);
 	if (!dev)
 		return -ENODEV;