Re: [Qemu-devel] [PATCH] virtio-balloon: fix integer overflow in BALLOON_CHANGE QMP event

[Eric Blake]

On 04/18/2013 11:05 AM, Luiz Capitulino wrote:
> Because dev->actual is uint32_t, the expression 'dev->actual <<
> VIRTIO_BALLOON_PFN_SHIFT' is truncated to 32 bits. This overflows when
> dev->actual >= 1048576.
> 
> To reproduce:
> 
>  1. Start a VM with a QMP socket and 5G of RAM
>  2. Connect to the QMP socket, negotiate capabilities and issue:
> 
>    { "execute":"balloon", "arguments": { "value": 1073741824 } }
> 
>  3. What the BALLOON_CHANGE QMP event, the last one will incorretly be:
> 
>    { "timestamp": { "seconds": 1366228965, "microseconds": 245466 },
>      "event": "BALLOON_CHANGE", "data": { "actual": 5368709120 } }
> 
> To fix it this commit casts it to ram_addr_t, which is ram_size's type.
> 
> Signed-off-by: Luiz Capitulino <address@hidden>
> ---
>  hw/virtio/virtio-balloon.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Reviewed-by: Eric Blake <address@hidden>

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

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