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Date: Thu, 8 Jun 2023 18:58:43 +0100
From: Lee Jones <lee@kernel.org>
To: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Eric Dumazet <edumazet@google.com>, xiyou.wangcong@gmail.com,
	jiri@resnulli.us, davem@davemloft.net, kuba@kernel.org,
	pabeni@redhat.com, linux-kernel@vger.kernel.org,
	netdev@vger.kernel.org, stable@kernel.org
Subject: Re: [PATCH v2 1/1] net/sched: cls_u32: Fix reference counter leak
 leading to overflow
Message-ID: <20230608175843.GA3635807@google.com>
References: <20230608072903.3404438-1-lee@kernel.org>
 <CANn89iKtkzTKhmeK15BO4uZOBQJhQWgQkaUgT+cxo+BwxE6Ofw@mail.gmail.com>
 <20230608074701.GD1930705@google.com>
 <CAM0EoM=osXFK7FLzF2QB3PvZ+W4sr=pnPD5jG1FjrzSbw-emWQ@mail.gmail.com>
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On Thu, 08 Jun 2023, Jamal Hadi Salim wrote:

> On Thu, Jun 8, 2023 at 3:47 AM Lee Jones <lee@kernel.org> wrote:
> >
> > On Thu, 08 Jun 2023, Eric Dumazet wrote:
> >
> > > On Thu, Jun 8, 2023 at 9:29 AM Lee Jones <lee@kernel.org> wrote:
> > > >
> > > > In the event of a failure in tcf_change_indev(), u32_set_parms() will
> > > > immediately return without decrementing the recently incremented
> > > > reference counter.  If this happens enough times, the counter will
> > > > rollover and the reference freed, leading to a double free which can be
> > > > used to do 'bad things'.
> > > >
> > > > In order to prevent this, move the point of possible failure above the
> > > > point where the reference counter is incremented.  Also save any
> > > > meaningful return values to be applied to the return data at the
> > > > appropriate point in time.
> > > >
> > > > This issue was caught with KASAN.
> > > >
> > > > Fixes: 705c7091262d ("net: sched: cls_u32: no need to call tcf_exts_change for newly allocated struct")
> > > > Suggested-by: Eric Dumazet <edumazet@google.com>
> > > > Signed-off-by: Lee Jones <lee@kernel.org>
> > > > ---
> > >
> > > Thanks Lee !
> >
> > No problem.  Thanks for your help.
> >
> > > Reviewed-by: Eric Dumazet <edumazet@google.com>
> 
> Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>

Thanks Jamal.

-- 
Lee Jones [李琼斯]