Bug#1117959: ipv6_route flags RTF_ADDRCONF and RTF_PREFIX_RT are not cleared when static on-link routes are added during IPv6 address configuration
HI Garri,
On Fri, Nov 21, 2025 at 11:07:39AM +0100, Garri Djavadyan wrote:
> On Sat, 2025-11-15 at 14:02 +0100, Garri Djavadyan wrote:
> > On Mon, 2025-11-10 at 17:54 +0100, Fernando Fernandez Mancera wrote:
> > >
> > >
> > > On 10/25/25 11:21 PM, Garri Djavadyan wrote:
> > > > On Sat, 2025-10-25 at 16:53 +0200, Salvatore Bonaccorso wrote:
> > > > > Hi Garri,
> > > > >
> > > > > On Sat, Oct 18, 2025 at 01:39:02AM -0700, Stephen Hemminger
> > > > > wrote:
> > > > > > On Thu, 16 Oct 2025 00:12:40 +0200
> > > > > > Garri Djavadyan <g.djavadyan@gmail.com> wrote:
> > > > > >
> > > > > > > Hi Everyone,
> > > > > > >
> > > > > > > A year ago I noticed a problem with handling ipv6_route
> > > > > > > flags
> > > > > > > that in
> > > > > > > some scenarios can lead to reachability issues. It was
> > > > > > > reported
> > > > > > > here:
> > > > > > >
> > > > > > > https://bugzilla.kernel.org/show_bug.cgi?id=219205
> > > > > > >
> > > > > > >
> > > > > > > Also it was recently reported in the Debian tracker after
> > > > > > > checking if
> > > > > > > the latest Debian stable is still affected:
> > > > > > >
> > > > > > > https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1117959
> > > > > > >
> > > > > > >
> > > > > > > Unfortunately, the Debian team cannot act on the report
> > > > > > > because
> > > > > > > no one
> > > > > > > from the upstream kernel team has confirmed if the report
> > > > > > > in
> > > > > > > the
> > > > > > > upstream tracker is valid or not. Therefore, I am checking
> > > > > > > if
> > > > > > > anyone
> > > > > > > can help confirm if the observed behavior is indeed a bug.
> > > > > > >
> > > > > > > Many thanks in advance!
> > > > > > >
> > > > > > > Regards,
> > > > > > > Garri
> > > > > > >
> > > > > >
> > > > > > Linux networking does not actively use kernel bugzilla.
> > > > > > I forward the reports to the mailing list, that is all.
> > > > > > After than sometimes developers go back and update bugzilla
> > > > > > but it is not required or expected.
> > > > >
> > > > > Garri, best action would likely be to really post your full
> > > > > report on
> > > > > netdev directly.
> > > > >
> > > > > Regards,
> > > > > Salvatore
> > > >
> > > >
> > > > Thank you for your suggestions Stephen and Salvatore.
> > > >
> > > > Below is the full report that was originally posted to the kernel
> > > > bugzilla a year ago. It is still reproducible with fresher
> > > > kernels.
> > > >
> > > > -----BEGIN REPORT-----
> > > > I noticed that the ipv6_route flags RTF_ADDRCONF and
> > > > RTF_PREFIX_RT
> > > > are
> > > > not cleared when static on-link routes are added during IPv6
> > > > address
> > > > configuration, and it leads to situations when the kernel updates
> > > > the
> > > > static on-link routes with expiration time.
> > > >
> > >
> > > This is indeed a bug, I have a patch already and I am doing some
> > > testing
> > > before sending it to net.git. I hope it can be sent tomorrow.
> > >
> > > Thanks,
> > > Fernando.
> >
> >
> > For the record, Fernando submitted the patch for review to net-next:
> >
> > https://lore.kernel.org/netdev/20251115095939.6967-1-fmancera@suse.de/
> >
> >
> > Regards,
> > Garri
>
> The patch has landed on linux-next:
>
> https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=f72514b3c5698e4b900b25345e09f9ed33123de6
That is great :)
> Salvatore, could you please clarify a few questions to which I could
> not find clear answers in the Debian Linux kernel handbook?
>
> - Should the patch first make it to the mainline or stable upstream
> trees before it is considered for acceptance in the Debian trees?
> - Will it be acceptable for both stable and oldstable Debian releases
> to include the fix considering that it can be seen as a security issue
> in some corner cases?
There is really no need for a Debian specific approach here in my
opinion. The patch has the correct fixes tags upstream so once it is
in mainline it should make it the way down to the stable series.
As you know Debian follows the upstream stable series. In case a fix
is now known to be okay (needs to be at least in mainline, ideally
already queued for stable), we might pick the commit as well for a
next upload in case it is urgent enough. But usually the best thing is
monitor the situation and help that the patch goes accepted in the
desired stable series and it will land in Debian correspondly as well
with the next rebased upload (both done at point release times but as
well in DSAs via a security upload).
The maybe bit shorter answer is, that the fix should be ideally at
least in mainline and well vetted that to go to the stable series, and
might then be picked as well in advance bit earlier than the actual
release in the upstream series.
Does this answers your question?
Regards,
Salvatore
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