netdev - Re: [Patch v2 net 1/2] netem: Fix skb duplication logic to prevent infinite loops

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <20250708191124.GB452973@horms.kernel.org>
Date: Tue, 8 Jul 2025 20:11:24 +0100
From: Simon Horman <horms@...nel.org>
To: Jamal Hadi Salim <jhs@...atatu.com>
Cc: Cong Wang <xiyou.wangcong@...il.com>, netdev@...r.kernel.org,
	will@...lsroot.io, stephen@...workplumber.org,
	Savino Dicanosa <savy@...t3mfailure.io>
Subject: Re: [Patch v2 net 1/2] netem: Fix skb duplication logic to prevent
 infinite loops

On Tue, Jul 08, 2025 at 09:19:50AM -0400, Jamal Hadi Salim wrote:
> On Tue, Jul 8, 2025 at 9:18 AM Simon Horman <horms@...nel.org> wrote:
> >
> > On Mon, Jul 07, 2025 at 12:50:14PM -0700, Cong Wang wrote:
> > > This patch refines the packet duplication handling in netem_enqueue() to ensure
> > > that only newly cloned skbs are marked as duplicates. This prevents scenarios
> > > where nested netem qdiscs with 100% duplication could cause infinite loops of
> > > skb duplication.
> > >
> > > By ensuring the duplicate flag is properly managed, this patch maintains skb
> > > integrity and avoids excessive packet duplication in complex qdisc setups.
> > >
> > > Now we could also get rid of the ugly temporary overwrite of
> > > q->duplicate.
> > >
> > > Fixes: 0afb51e72855 ("[PKT_SCHED]: netem: reinsert for duplication")
> > > Reported-by: William Liu <will@...lsroot.io>
> > > Reported-by: Savino Dicanosa <savy@...t3mfailure.io>
> > > Signed-off-by: Cong Wang <xiyou.wangcong@...il.com>
> >
> > Reviewed-by: Simon Horman <horms@...nel.org>
> 
> Simon,
> This patch wont work - see the sample config i presented.

Sorry, I convinced myself it would.
But it seems I was wrong.