Some futex functions in futex.c for Linux kernel 2.6.x perform get_user calls while holding the mmap_sem semaphore, which could allow local users to cause a deadlock condition in do_page_fault by triggering get_user faults while another thread is executing mmap or other functions.

cryptoloop on Linux kernel 2.6.x, when used on certain file systems with a block size 1024 or greater, has certain "IV computation" weaknesses that allow watermarked files to be detected without decryption.