The gfs2_lock function in the Linux kernel before 2.6.34-rc1-next-20100312, and the gfs_lock function in the Linux kernel on Red Hat Enterprise Linux (RHEL) 5 and 6, does not properly remove POSIX locks on files that are setgid without group-execute permission, which allows local users to cause a denial of service (BUG and system crash) by locking a file on a (1) GFS or (2) GFS2 filesystem, and then changing this file's permissions.