ipv6: Avoid unnecessary temporary addresses being generated

tmp_prefered_lft is an offset to ifp->tstamp, not now. Therefore
age needs to be added to the condition.

Age calculation in ipv6_create_tempaddr is different from the one
in addrconf_verify and doesn't consider ADDRCONF_TIMER_FUZZ_MINUS.
This can cause age in ipv6_create_tempaddr to be less than the one
in addrconf_verify and therefore unnecessary temporary address to
be generated.
Use age calculation as in addrconf_modify to avoid this.

Signed-off-by: Heiner Kallweit <heiner.kallweit@web.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 4 insertions, 1 deletions

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index fdbfeca36d63..344e972426df 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -1103,8 +1103,11 @@ retry:
          * Lifetime is greater than REGEN_ADVANCE time units.  In particular,
          * an implementation must not create a temporary address with a zero
          * Preferred Lifetime.
+         * Use age calculation as in addrconf_verify to avoid unnecessary
+         * temporary addresses being generated.
          */
-        if (tmp_prefered_lft <= regen_advance) {
+        age = (now - tmp_tstamp + ADDRCONF_TIMER_FUZZ_MINUS) / HZ;
+        if (tmp_prefered_lft <= regen_advance + age) {
                 in6_ifa_put(ifp);
                 in6_dev_put(idev);
                 ret = -1;