Multiple race conditions in the terminal layer in Linux 2.4.x, and 2.6.x before 2.6.9, allow (1) local users to obtain portions of kernel data via a TIOCSETD ioctl call to a terminal interface that is being accessed by another thread, or (2) remote attackers to cause a denial of service (panic) by switching from console to PPP line discipline, then quickly sending data that is received during the switch.