Bug 71591 - Temporary address re-generated when it should not (public address about to expire)

Bug 71591 - Temporary address re-generated when it should not (public address about to expire)

[Heiner Kallweit]

Recently I faced the issue that a public address was about to expire and 
3s before expiry a new temporary address was generated which instantly 
went into deprecated state.
This didn't do any harm however it's wrong IMHO. Problem seems to be in 
function ipv6_create_tempaddr in addrconf.c.
A new temporary address is generated if this condition is met: 
tmp_prefered_lft > regen_advance
tmp_prefered_lft however is an offset from tstamp, not from now.
This condition only checks that the new address is preferred until more 
than regen_advance from tstamp,
but it should check that the new address is preferred until more than 
regen_advance from now.

I submitted this issue to kernel bugzilla -> 71591
Hannes asked me to propose a patch, here it comes.

Rgds, Heiner

diff -uNr linux-3.10.32.vanilla/net/ipv6/addrconf.c 
linux-3.10.32.patched/net/ipv6/addrconf.c
--- linux-3.10.32.vanilla/net/ipv6/addrconf.c    2014-02-22 
14:41:54.000000000 -0600
+++ linux-3.10.32.patched/net/ipv6/addrconf.c    2014-03-06 
17:07:12.953699438 -0600
@@ -1111,8 +1111,9 @@
       * Lifetime is greater than REGEN_ADVANCE time units.  In particular,
       * an implementation must not create a temporary address with a zero
       * Preferred Lifetime.
+     * Note that tmp_prefered_lft is relative to ifp->tstamp not now.
       */
-    if (tmp_prefered_lft <= regen_advance) {
+    if (tmp_prefered_lft <= regen_advance + age) {
          in6_ifa_put(ifp);
          in6_dev_put(idev);
          ret = -1;

Bug 71591 - Temporary address re-generated when it should not (public address about to expire)

[Heiner Kallweit]

Recently I faced the issue that a public address was about to expire and 
3s before expiry a new temporary address was generated which instantly 
went into deprecated state.
This didn't do any harm however it's wrong IMHO. Problem seems to be in 
function ipv6_create_tempaddr in addrconf.c.
A new temporary address is generated if this condition is met: 
tmp_prefered_lft > regen_advance
tmp_prefered_lft however is an offset from tstamp, not from now.
This condition only checks that the new address is preferred until more 
than regen_advance from tstamp,
but it should check that the new address is preferred until more than 
regen_advance from now.

I submitted this issue to kernel bugzilla -> 71591
Hannes asked me to propose a patch, here it comes.

Rgds, Heiner

diff -uNr linux-3.10.32.vanilla/net/ipv6/addrconf.c 
linux-3.10.32.patched/net/ipv6/addrconf.c
--- linux-3.10.32.vanilla/net/ipv6/addrconf.c    2014-02-22 
14:41:54.000000000 -0600
+++ linux-3.10.32.patched/net/ipv6/addrconf.c    2014-03-06 
17:07:12.953699438 -0600
@@ -1111,8 +1111,9 @@
       * Lifetime is greater than REGEN_ADVANCE time units.  In particular,
       * an implementation must not create a temporary address with a zero
       * Preferred Lifetime.
+     * Note that tmp_prefered_lft is relative to ifp->tstamp not now.
       */
-    if (tmp_prefered_lft <= regen_advance) {
+    if (tmp_prefered_lft <= regen_advance + age) {
          in6_ifa_put(ifp);
          in6_dev_put(idev);
          ret = -1;

Bug 71591 - Temporary address re-generated when it should not (public address about to expire)

[Heiner Kallweit]

Recently I faced the issue that a public address was about to expire and 
3s before expiry a new temporary address was generated which instantly 
went into deprecated state.
This didn't do any harm however it's wrong IMHO. Problem seems to be in 
function ipv6_create_tempaddr in addrconf.c.
A new temporary address is generated if this condition is met: 
tmp_prefered_lft > regen_advance
tmp_prefered_lft however is an offset from tstamp, not from now.
This condition only checks that the new address is preferred until more 
than regen_advance from tstamp,
but it should check that the new address is preferred until more than 
regen_advance from now.

I submitted this issue to kernel bugzilla -> 71591
Hannes asked me to propose a patch, here it comes.

Rgds, Heiner

diff -uNr linux-3.10.32.vanilla/net/ipv6/addrconf.c 
linux-3.10.32.patched/net/ipv6/addrconf.c
--- linux-3.10.32.vanilla/net/ipv6/addrconf.c    2014-02-22 
14:41:54.000000000 -0600
+++ linux-3.10.32.patched/net/ipv6/addrconf.c    2014-03-06 
17:07:12.953699438 -0600
@@ -1111,8 +1111,9 @@
       * Lifetime is greater than REGEN_ADVANCE time units.  In particular,
       * an implementation must not create a temporary address with a zero
       * Preferred Lifetime.
+     * Note that tmp_prefered_lft is relative to ifp->tstamp not now.
       */
-    if (tmp_prefered_lft <= regen_advance) {
+    if (tmp_prefered_lft <= regen_advance + age) {
          in6_ifa_put(ifp);
          in6_dev_put(idev);
          ret = -1;

Re: Bug 71591 - Temporary address re-generated when it should not (public address about to expire)

[Hannes Frederic Sowa]

On Thu, Mar 06, 2014 at 05:38:21PM +0100, Heiner Kallweit wrote:
> Recently I faced the issue that a public address was about to expire and 
> 3s before expiry a new temporary address was generated which instantly 
> went into deprecated state.
> This didn't do any harm however it's wrong IMHO. Problem seems to be in 
> function ipv6_create_tempaddr in addrconf.c.
> A new temporary address is generated if this condition is met: 
> tmp_prefered_lft > regen_advance
> tmp_prefered_lft however is an offset from tstamp, not from now.
> This condition only checks that the new address is preferred until more 
> than regen_advance from tstamp,
> but it should check that the new address is preferred until more than 
> regen_advance from now.
> 
> I submitted this issue to kernel bugzilla -> 71591
> Hannes asked me to propose a patch, here it comes.

You would need to follow Documentation/SubmittingPatches and provide a proper
signed-off-by.

Basically if scripts/checkpatch.pl --strict doesn't complain on your patch any
more, then you're ready to submit.

Otherwise the patch looks good to me.

Thanks,

  Hannes

Re: Bug 71591 - Temporary address re-generated when it should not (public address about to expire)

[Heiner Kallweit]

Thanks for the hint on the correct procedure. Next try ..
Output from checkpatch.p --strict
total: 0 errors, 0 warnings, 0 checks, 10 lines checked
patch-3.10.32-ipv6_create_tempaddr has no obvious style problems and is 
ready for submission.

diff -upNr linux-3.10.32.vanilla/net/ipv6/addrconf.c 
linux-3.10.32.patched/net/ipv6/addrconf.c
--- linux-3.10.32.vanilla/net/ipv6/addrconf.c    2014-02-22 
14:41:54.000000000 -0600
+++ linux-3.10.32.patched/net/ipv6/addrconf.c    2014-03-06 
17:07:12.953699438 -0600
@@ -1111,8 +1111,9 @@ retry:
       * Lifetime is greater than REGEN_ADVANCE time units.  In particular,
       * an implementation must not create a temporary address with a zero
       * Preferred Lifetime.
+     * Note that tmp_prefered_lft is relative to ifp->tstamp not now.
       */
-    if (tmp_prefered_lft <= regen_advance) {
+    if (tmp_prefered_lft <= regen_advance + age) {
          in6_ifa_put(ifp);
          in6_dev_put(idev);
          ret = -1;
Signed-off-by: Heiner Kallweit <heiner.kallweit@web.de>

Rgds,
Heiner


Am 06.03.2014 17:43, schrieb Hannes Frederic Sowa:
> On Thu, Mar 06, 2014 at 05:38:21PM +0100, Heiner Kallweit wrote:
>> Recently I faced the issue that a public address was about to expire and
>> 3s before expiry a new temporary address was generated which instantly
>> went into deprecated state.
>> This didn't do any harm however it's wrong IMHO. Problem seems to be in
>> function ipv6_create_tempaddr in addrconf.c.
>> A new temporary address is generated if this condition is met:
>> tmp_prefered_lft > regen_advance
>> tmp_prefered_lft however is an offset from tstamp, not from now.
>> This condition only checks that the new address is preferred until more
>> than regen_advance from tstamp,
>> but it should check that the new address is preferred until more than
>> regen_advance from now.
>>
>> I submitted this issue to kernel bugzilla -> 71591
>> Hannes asked me to propose a patch, here it comes.
> You would need to follow Documentation/SubmittingPatches and provide a proper
> signed-off-by.
>
> Basically if scripts/checkpatch.pl --strict doesn't complain on your patch any
> more, then you're ready to submit.
>
> Otherwise the patch looks good to me.
>
> Thanks,
>
>    Hannes
>
>