Quoting from the upstream commit: Almost all r128's private ioctls require that the CCE state has already been initialised. However, most do not test that this has been done, and will proceed to dereference a null pointer. This may result in a security vulnerability, since some ioctls are unprivileged.

This adds a macro for the common initialisation test and changes all ioctl implementations that require prior initialisation to use that macro.

Also, r128doinitcce() does not test that the CCE state has not been initialised already. Repeated initialisation may lead to a crash or resource leak. This adds that test.

http://git.kernel.org/linus/7dc482dfeeeefcfd000d4271c4626937406756d7

Other references: http://secunia.com/advisories/36707/

Memory leak in the appletalk subsystem in the Linux kernel 2.4.x through 2.4.37.6 and 2.6.x through 2.6.31, when the appletalk and ipddp modules are loaded but the ipddp"N" device is not found, allows remote attackers to cause a denial of service (memory consumption) via IP-DDP datagrams.