2023-06-08 07:50:16

by Eric Dumazet

Subject: Re: [PATCH v2 1/1] net/sched: cls_u32: Fix reference counter leak leading to overflow

On Thu, Jun 8, 2023 at 9:29 AM Lee Jones <[email protected]> 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 <[email protected]>
> Signed-off-by: Lee Jones <[email protected]>
> ---

Thanks Lee !

Reviewed-by: Eric Dumazet <[email protected]>

2023-06-08 08:22:18

by Lee Jones

Subject: Re: [PATCH v2 1/1] net/sched: cls_u32: Fix reference counter leak leading to overflow

On Thu, 08 Jun 2023, Eric Dumazet wrote:

> On Thu, Jun 8, 2023 at 9:29 AM Lee Jones <[email protected]> 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 <[email protected]>
> > Signed-off-by: Lee Jones <[email protected]>
> > ---
>
> Thanks Lee !

No problem. Thanks for your help.

> Reviewed-by: Eric Dumazet <[email protected]>

--
Lee Jones [李琼斯]

2023-06-08 16:50:34

by Jamal Hadi Salim

Subject: Re: [PATCH v2 1/1] net/sched: cls_u32: Fix reference counter leak leading to overflow

On Thu, Jun 8, 2023 at 3:47 AM Lee Jones <[email protected]> wrote:
>
> On Thu, 08 Jun 2023, Eric Dumazet wrote:
>
> > On Thu, Jun 8, 2023 at 9:29 AM Lee Jones <[email protected]> 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 <[email protected]>
> > > Signed-off-by: Lee Jones <[email protected]>
> > > ---
> >
> > Thanks Lee !
>
> No problem. Thanks for your help.
>
> > Reviewed-by: Eric Dumazet <[email protected]>

Acked-by: Jamal Hadi Salim <[email protected]>

cheers,
jamal

> --
> Lee Jones [李琼斯]

2023-06-08 18:15:13

by Lee Jones

Subject: Re: [PATCH v2 1/1] net/sched: cls_u32: Fix reference counter leak leading to overflow

On Thu, 08 Jun 2023, Jamal Hadi Salim wrote:

> On Thu, Jun 8, 2023 at 3:47 AM Lee Jones <[email protected]> wrote:
> >
> > On Thu, 08 Jun 2023, Eric Dumazet wrote:
> >
> > > On Thu, Jun 8, 2023 at 9:29 AM Lee Jones <[email protected]> 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 <[email protected]>
> > > > Signed-off-by: Lee Jones <[email protected]>
> > > > ---
> > >
> > > Thanks Lee !
> >
> > No problem. Thanks for your help.
> >
> > > Reviewed-by: Eric Dumazet <[email protected]>
>
> Acked-by: Jamal Hadi Salim <[email protected]>

Thanks Jamal.

--
Lee Jones [李琼斯]