kernel: local privilege escalation via /sys/kernel/debug/acpi/custom_method

The ACPI subsystem in the Linux kernel before 2.6.36.2 uses 0222 permissions for the debugfs custommethod file, which allows local users to gain privileges by placing a custom ACPI method in the ACPI interpreter tables, related to the acpidebugfsinit function in drivers/acpi/debugfs.c...