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. Watch for BALLOON_CHANGE QMP events, 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>
Reviewed-by: Eric Blake <eblake@redhat.com>
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));
}
}