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Bug#1136792: linux-image-7.0.4+deb13-amd64: ipv6 temp addresses renew prematurely when removing interface

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On Sat, May 16, 2026 at 03:08:10AM +0200, Andreas Ferber wrote:
> Package: src:linux
> Version: 7.0.4-1~bpo13+1
> Severity: normal
> Tags: ipv6
> X-Debbugs-Cc: debian-amd64@lists.debian.org
> User: debian-amd64@lists.debian.org
> Usertags: amd64
> 
> Hi,
> 
> On my LAN interface (br0) I have IPv6 privacy extensions enabled (sysctl
> net.ipv6.conf.br0.use_tempaddr=2). Since upgrading the kernel to this
> version the temporary IPv6 addresses are renewed prematurely whenever a
> network interface is removed (e.g. due to stopping a docker container
> which removes the associated veth device). Or more precisely, the
> renewal happens when the first router advertisement is received after a
> network interface has been removed.
> 
> Expected behavior is that removal of an unrelated network interface
> should have no influence on when the temp address is renewed.
> 
> Note that in order to trigger this issue the removed interface doesn't
> have to be part of the br0 bridge where the temp addresses reside, any
> interface will do (for example running "ip link add dummy0 type dummy;
> ip link del dummy0"). Even the deletion of an interface that has IPv6
> disabled (net.ipv6.conf.dummy0.disable_ipv6=1) triggers the issue.
> 
> Just adding a new interface doesn't trigger the issue, only removing one
> does.
> 
> Note that the very short lifetimes on the public addresses
> (2a02:908:...) that you can see in the system info below doesn't have
> anything to do with the issue, it's just a quirk of my ISP. I'm seeing
> the same behavior on another machine in a different network where the
> lifetimes are much longer.

As I understand you have a reliable reproducer for this. Can you thus
please test the newester 7.0.7-1 in unstable and report back if the
problem exists.

If it still exists, can you please bisect the changes, from which
kernel have you updated? If it was not from 7.0.3, test down more
closely the Debian released versions, then once the two Debian
released versions changing behaviour are close bisect the changes in
the upstream versions to identify which commit changes the behaviour.

Do you need further instructions on how to bisect?

Regards,
Salvatore

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Bug#1136792: linux-image-7.0.4+deb13-amd64: ipv6 temp addresses renew prematurely when removing interface Andreas Ferber <af+debian-bugregports@chaos-agency.de> - 2026-05-16 03:30 +0200
  Bug#1136792: linux-image-7.0.4+deb13-amd64: ipv6 temp addresses renew prematurely when removing interface Salvatore Bonaccorso <carnil@debian.org> - 2026-05-16 08:30 +0200
  Processed: Re: Bug#1136792: linux-image-7.0.4+deb13-amd64: ipv6  temp addresses renew prematurely when removing interface "Debian Bug Tracking System" <owner@bugs.debian.org> - 2026-05-16 08:30 +0200

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