madvise_remove in Linux kernel 2.6.16 up to 2.6.16.6 does not follow file and mmap restrictions, which allows local users to bypass IPC permissions and replace portions of readonly tmpfs files with zeroes, aka the MADV_REMOVE vulnerability.  NOTE: this description was originally written in a way that combined two separate issues.  The mprotect issue now has a separate name, CVE-2006-2071.