| Message ID | 20130418130552.2d319e91@redhat.com |
|---|---|
| State | New |
| Headers | show |
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 <lcapitulino@redhat.com> > --- > hw/virtio/virtio-balloon.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) Reviewed-by: Eric Blake <eblake@redhat.com>
diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c index c2c446e..76e32ce 100644 --- a/hw/virtio/virtio-balloon.c +++ b/hw/virtio/virtio-balloon.c @@ -275,7 +275,7 @@ static void virtio_balloon_set_config(VirtIODevice *vdev, dev->actual = le32_to_cpu(config.actual); if (dev->actual != oldactual) { qemu_balloon_changed(ram_size - - (dev->actual << VIRTIO_BALLOON_PFN_SHIFT)); + ((ram_addr_t) dev->actual << VIRTIO_BALLOON_PFN_SHIFT)); } }
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 <lcapitulino@redhat.com> --- hw/virtio/virtio-balloon.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)