Re: [PATCH] batman-adv: Release references to inactive interfaces

[Sven Eckelmann <sven@narfation.org>]

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On Friday, 17 October 2025 13:18:20 CEST Tetsuo Handa wrote:
> Is this patch recognized?

Who should recognize the patch?

https://git.open-mesh.org/linux-merge.git/commit/?id=f12b69d8f22824a07f17c1399c99757072de73e0

Regards,
	Sven

> 
> On 2025/09/28 3:01, Sven Eckelmann wrote:
> > Trying to dump the originators or the neighbors via netlink for a meshif
> > with an inactive primary interface is not allowed. The dump functions were
> > checking this correctly but they didn't handle non-existing primary
> > interfaces and existing _inactive_ interfaces differently.
> > 
> > (Primary) batadv_hard_ifaces hold a references to a net_device. And
> > accessing them is only allowed when either being in a RCU/spinlock
> > protected section or when holding a valid reference to them. The netlink
> > dump functions use the latter.
> > 
> > But because the missing specific error handling for inactive primary
> > interfaces, the reference was never dropped. This reference counting error
> > was only detected when the interface should have been removed from the
> > system:
> > 
> >   unregister_netdevice: waiting for batadv_slave_0 to become free. Usage count = 2
> > 
> > Fixes: 50eddf397ac3 ("batman-adv: netlink: reduce duplicate code by returning interfaces")
> > Reported-by: syzbot+881d65229ca4f9ae8c84@syzkaller.appspotmail.com
> > Reported-by: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
> > Signed-off-by: Sven Eckelmann <sven@narfation.org>
> > ---
> >  net/batman-adv/originator.c | 14 ++++++++++++--
> >  1 file changed, 12 insertions(+), 2 deletions(-)
> 


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