Re: [Qemu-devel] [PATCH v2] virtio-balloon: fix integer overflow in memory stats feature

[Luiz Capitulino <lcapitulino@redhat.com>]

On Tue, 16 Sep 2014 18:02:54 +0300
"Michael S. Tsirkin" <mst@redhat.com> wrote:

> On Tue, Sep 16, 2014 at 09:39:50AM -0400, Luiz Capitulino wrote:
> > When a QMP client changes the polling interval time by setting
> > the guest-stats-polling-interval property, the interval value
> > is stored and manipulated as an int64_t variable.
> > 
> > However, the balloon_stats_change_timer() function, which is
> > used to set the actual timer with the interval value, takes
> > an int instead, causing an overflow for big interval values.
> > 
> > This commit fix this bug by changing balloon_stats_change_timer()
> > to take an int64_t and also it limits the polling interval value
> > to UINT_MAX to avoid other kinds of overflow.
> > 
> > Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
> 
> OK but pls remember to Cc qemu-stable on bugfixes.

I did.

> 
> > ---
> 
> >  hw/virtio/virtio-balloon.c | 7 ++++++-
> >  1 file changed, 6 insertions(+), 1 deletion(-)
> > 
> > diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
> > index 2c30b3d..b5cf7ca 100644
> > --- a/hw/virtio/virtio-balloon.c
> > +++ b/hw/virtio/virtio-balloon.c
> > @@ -87,7 +87,7 @@ static void balloon_stats_destroy_timer(VirtIOBalloon *s)
> >      }
> >  }
> >  
> > -static void balloon_stats_change_timer(VirtIOBalloon *s, int secs)
> > +static void balloon_stats_change_timer(VirtIOBalloon *s, int64_t secs)
> >  {
> >      timer_mod(s->stats_timer, qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) + secs * 1000);
> >  }
> > @@ -170,6 +170,11 @@ static void balloon_stats_set_poll_interval(Object *obj, struct Visitor *v,
> >          return;
> >      }
> >  
> > +    if (value > UINT_MAX) {
> > +        error_setg(errp, "timer value is too big");
> > +        return;
> > +    }
> > +
> >      if (value == s->stats_poll_interval) {
> >          return;
> >      }
> > -- 
> > 1.9.3
> > 
>