linux-kernel - [PATCH 3.11 20/46] ipv6: Avoid unnecessary temporary addresses being generated

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Message-Id: <1397644322-13905-21-git-send-email-luis.henriques@canonical.com>
Date:	Wed, 16 Apr 2014 11:31:36 +0100
From:	Luis Henriques <luis.henriques@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Heiner Kallweit <heiner.kallweit@....de>,
	"David S. Miller" <davem@...emloft.net>,
	Luis Henriques <luis.henriques@...onical.com>
Subject: [PATCH 3.11 20/46] ipv6: Avoid unnecessary temporary addresses being generated

3.11.10.8 -stable review patch.  If anyone has any objections, please let me know.

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

From: Heiner Kallweit <heiner.kallweit@....de>

commit ecab67015ef6e3f3635551dcc9971cf363cc1cd5 upstream.

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@....de>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Luis Henriques <luis.henriques@...onical.com>
---
 net/ipv6/addrconf.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 0f99f7b..a6ddced 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -1113,8 +1113,11 @@ 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;
-- 
1.9.1

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