ipv6: Avoid unnecessary temporary addresses being generated

[ Upstream commit ecab67015ef6e3f3635551dcc9971cf363cc1cd5 ]

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>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 5d41293..b9edff0 100644 (file)
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -900,8 +900,11 @@ 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;