return inet6_addr_add(ifm->ifa_index, pfx, ifm->ifa_prefixlen);
 }
 
+/* Maximum length of ifa_cacheinfo attributes */
+#define INET6_IFADDR_RTA_SPACE \
+               RTA_SPACE(16) /* IFA_ADDRESS */ + \
+               RTA_SPACE(sizeof(struct ifa_cacheinfo)) /* CACHEINFO */
+
 static int inet6_fill_ifaddr(struct sk_buff *skb, struct inet6_ifaddr *ifa,
                             u32 pid, u32 seq, int event, unsigned int flags)
 {
 static void inet6_ifa_notify(int event, struct inet6_ifaddr *ifa)
 {
        struct sk_buff *skb;
-       int size = NLMSG_SPACE(sizeof(struct ifaddrmsg)+128);
+       int size = NLMSG_SPACE(sizeof(struct ifaddrmsg) + INET6_IFADDR_RTA_SPACE);
 
        skb = alloc_skb(size, GFP_ATOMIC);
        if (!skb) {
 #endif
 }
 
+/* Maximum length of ifinfomsg attributes */
+#define INET6_IFINFO_RTA_SPACE \
+               RTA_SPACE(IFNAMSIZ) /* IFNAME */ + \
+               RTA_SPACE(MAX_ADDR_LEN) /* ADDRESS */ + \
+               RTA_SPACE(sizeof(u32)) /* MTU */ + \
+               RTA_SPACE(sizeof(int)) /* LINK */ + \
+               RTA_SPACE(0) /* PROTINFO */ + \
+               RTA_SPACE(sizeof(u32)) /* FLAGS */ + \
+               RTA_SPACE(sizeof(struct ifla_cacheinfo)) /* CACHEINFO */ + \
+               RTA_SPACE(sizeof(__s32[DEVCONF_MAX])) /* CONF */
+
 static int inet6_fill_ifinfo(struct sk_buff *skb, struct inet6_dev *idev, 
                             u32 pid, u32 seq, int event, unsigned int flags)
 {
 void inet6_ifinfo_notify(int event, struct inet6_dev *idev)
 {
        struct sk_buff *skb;
-       /* 128 bytes ?? */
-       int size = NLMSG_SPACE(sizeof(struct ifinfomsg)+128);
+       int size = NLMSG_SPACE(sizeof(struct ifinfomsg) + INET6_IFINFO_RTA_SPACE);
        
        skb = alloc_skb(size, GFP_ATOMIC);
        if (!skb) {
        netlink_broadcast(rtnl, skb, 0, RTNLGRP_IPV6_IFINFO, GFP_ATOMIC);
 }
 
+/* Maximum length of prefix_cacheinfo attributes */
+#define INET6_PREFIX_RTA_SPACE \
+               RTA_SPACE(sizeof(((struct prefix_info *)NULL)->prefix)) /* ADDRESS */ + \
+               RTA_SPACE(sizeof(struct prefix_cacheinfo)) /* CACHEINFO */
+
 static int inet6_fill_prefix(struct sk_buff *skb, struct inet6_dev *idev,
                        struct prefix_info *pinfo, u32 pid, u32 seq, 
                        int event, unsigned int flags)
                         struct prefix_info *pinfo)
 {
        struct sk_buff *skb;
-       int size = NLMSG_SPACE(sizeof(struct prefixmsg)+128);
+       int size = NLMSG_SPACE(sizeof(struct prefixmsg) + INET6_PREFIX_RTA_SPACE);
 
        skb = alloc_skb(size, GFP_ATOMIC);
        if (!skb) {