Re: [PATCH 1/1] net: bridge: fix a bug on using a neighbour cache entry without checking its state

[kchen]

From: David Miller <davem@xxxxxxxxxxxxx>
Date: Mon, 07 Jan 2019 09:10:31 -0800

> From: David Miller <davem@xxxxxxxxxxxxx>
>
> From: kchen <kchen@xxxxxxxxxxxx>
> Date: Sun,  6 Jan 2019 11:28:13 +0800
>
> > From: JianJhen Chen <kchen@xxxxxxxxxxxx>
> >
> > When handling DNAT'ed packets on a bridge device, the neighbour cache entry
> > from lookup was used without checking its state. It means that a cache entry
> > in the NUD_STALE state will be used directly instead of entering the NUD_DELAY
> > state to confirm the reachability of the neighbor.
> >
> > This problem becomes worse after commit 2724680bceee ("neigh: Keep neighbour
> > cache entries if number of them is small enough."), since all neighbour cache
> > entries in the NUD_STALE state will be kept in the neighbour table as long as
> > the number of cache entries does not exceed the value specified in gc_thresh1.
> >
> > This commit validates the state of a neighbour cache entry before using
> > the entry.
> >
> > Signed-off-by: JianJhen Chen <kchen@xxxxxxxxxxxx>
> > Reviewed-by: JinLin Chen <jlchen@xxxxxxxxxxxx>
>
> Indeed, this looks correct.
>
> Applied and queued up for -stable, thanks.

Thank you for the confirmation.