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

["Michael S. Tsirkin" <mst@redhat.com>]

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.

> ---

>  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
>