[PATCH 3.2 06/94] ipv6: Avoid unnecessary temporary addresses being generated

From: Ben Hutchings
Date: Sun Apr 27 2014 - 22:10:32 EST


3.2.58-rc1 review patch. If anyone has any objections, please let me know.

------------------

From: Heiner Kallweit <heiner.kallweit@xxxxxx>

[ 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@xxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
net/ipv6/addrconf.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

--- 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;

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