Reported by Dave Jones, currently we have: --w--w--w-. 1 root root 0 2010-11-11 14:56 /sys/kernel/debug/acpi/custom_method which is just crazy. Change this to --w-------. This custom_method file allows to inject custom ACPI methods into the ACPI interpreter tables. This control file was introduced with world writeable permissions in Linux Kernel 2.6.33. Introduced in: http://git.kernel.org/linus/a1a541d86f50a9957beeedb122a035870d602647 http://git.kernel.org/linus/a25ee9200eef07377e1703697afbb5d81f89e500 Fixed in: http://git.kernel.org/linus/ed3aada1bf34c5a9e98af167f125f8a740fc726a
Statement: This issue did not affect the version of Linux kernel as shipped with Red Hat Enterprise Linux 4, 5, and 6 as they did not include upstream commit a1a541d8 and a25ee920 that introduced the problem. This has been addressed in Red Hat Enterprise MRG via https://rhn.redhat.com/errata/RHSA-2011-0330.html. Notes: This requires debugfs to be mounted on a local system in order to have access to the custom_method file. Debugfs is not mounted by default. You need to run "mount -t debugfs nodev /sys/kernel/debug" as root first.
This issue has been addressed in following products: MRG for RHEL-5 Via RHSA-2011:0330 https://rhn.redhat.com/errata/RHSA-2011-0330.html