Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Thu, 8 Jun 2023 08:47:01 +0100
From:   Lee Jones <lee@kernel.org>
To:     Eric Dumazet <edumazet@google.com>
Cc:     jhs@mojatatu.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: <20230608074701.GD1930705@google.com>
References: <20230608072903.3404438-1-lee@kernel.org>
 <CANn89iKtkzTKhmeK15BO4uZOBQJhQWgQkaUgT+cxo+BwxE6Ofw@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
Content-Transfer-Encoding: 8bit
In-Reply-To: <CANn89iKtkzTKhmeK15BO4uZOBQJhQWgQkaUgT+cxo+BwxE6Ofw@mail.gmail.com>
Precedence: bulk

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>

-- 
Lee Jones [李琼斯]