kexec-tools: incorrect permissions on kdump dmesg file

A flaw was found in the permissions of a log file created by kexec-tools. This flaw allows a local unprivileged user to read this file and leak kernel internal information from a previous panic. The highest threat from this vulnerability is to confidentiality. This flaw affects kexec-tools shipped by Fedora versions prior to 2.0.21-8 and RHEL versions prior to 2.0.20-47.