In FreeBSD before 11.1-STABLE, 11.1-RELEASE-p4, 11.0-RELEASE-p15, 10.4-STABLE, 10.4-RELEASE-p3, and 10.3-RELEASE-p24, the kernel does not properly clear the…

In FreeBSD before 11.1-STABLE, 11.1-RELEASE-p4, 11.0-RELEASE-p15, 10.4-STABLE, 10.4-RELEASE-p3, and 10.3-RELEASE-p24, the kernel does not properly clear the memory of the kld_file_stat structure before filling the data. Since the structure filled by the kernel is allocated on the kernel stack and copied to userspace, a leak of information from the kernel stack is possible. As a result, some bytes from the kernel stack can be observed in userspace.