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

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

[Luiz Capitulino]

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>
---
 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

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

[Eric Blake]

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On 09/16/2014 07:39 AM, 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>
> ---
>  hw/virtio/virtio-balloon.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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

[Luiz Capitulino]

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
> > 
> 

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

[Michael S. Tsirkin]

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
> 

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

[Markus Armbruster]

Luiz Capitulino <lcapitulino@redhat.com> writes:

> 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>

Reviewed-by: Markus Armbruster <armbru@redhat.com>