virDomainGetDiskErrors uses the weird semantics where we make the
caller query for the number of elements and then pass pre-allocated
structure.
The cleanup section errorneously used the 'count' variable to free the
allocated elements for the API but 'count' can be '-1' in cases when the
API returns failure, thus attempting to free beyond the end of the
array.
Resolves: https://gitlab.com/libvirt/libvirt/-/issues/155
Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Pavel Hrdina <phrdina@redhat.com>