MEDIUM
The tomoyo_mount_acl function in security/tomoyo/mount.c in the Linux kernel before 2.6.39.2 calls the kern_path function with arguments taken directly from a mount system call, which allows local users to cause a denial of service (OOPS) or possibly have unspecified other impact via a NULL value for the device name.
http://ftp.osuosl.org/pub/linux/kernel/v2.6/ChangeLog-2.6.39.2
http://marc.info/?l=bugtraq&m=139447903326211&w=2
http://www.openwall.com/lists/oss-security/2011/07/01/5
https://github.com/torvalds/linux/commit/4e78c724d47e2342aa8fde61f6b8536f662f795f