Multiple race conditions in fs/pipe.c in the Linux kernel before 2.6.32-rc6 allow local users to cause a denial of service (NULL pointer dereference and system crash) or gain privileges by attempting to open an anonymous pipe via a /proc//fd/ pathname.

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/