Re: [PATCH 4.19 164/213] netfilter: nft_set_rbtree: Switch to node list walk for overlap detection

[Pablo Neira Ayuso <pablo@netfilter.org>]

On Mon, Jul 01, 2024 at 11:48:51PM +0200, Pablo Neira Ayuso wrote:
> On Mon, Jul 01, 2024 at 10:51:17PM +0200, Ben Hutchings wrote:
> > On Thu, 2024-06-13 at 13:33 +0200, Greg Kroah-Hartman wrote:
> > > 4.19-stable review patch.  If anyone has any objections, please let me know.
> > > 
> > > ------------------
> > > 
> > > From: Pablo Neira Ayuso <pablo@netfilter.org>
> > > 
> > > commit c9e6978e2725a7d4b6cd23b2facd3f11422c0643 upstream.
> > [...]
> > 
> > This turns out to cause a regression for nftables user-space versions
> > older than v0.9.3, specifically before:
> > 
> > commit a4ec053812610400b7a9e6c060d8b7589dedd5b1
> > Author: Pablo Neira Ayuso <pablo@netfilter.org>
> > Date:   Wed Oct 9 11:54:32 2019 +0200
> >  
> >     segtree: always close interval in non-anonymous sets
> 
> This is really fixing up userspace as the commit describes, otherwise
> incremental updates are not possible on a set/map.
> 
> > Should nft_set_rbtree detect and fix-up the bad set messages that
> > nftables user-space used to send?
> 
> Problem is that a non-anonymous set really needs close intervals,
> otherwise incremental updates on it are not possible.
> 
> It should be possible to backport a fix for such nftables version.
> 
> I can see Debian 10 (Buster, oldoldstable) is using 0.9.0 but it was
> discontinued in june 2022? But who is using such an old userspace version?

Oh, I misread, it is still supported in oldoldstable in Debian.

Then, userspace really needs this fix, because incremental updates on
a set are not really possible.

I can take a look and send a backport of this for nftables 0.9.0.