The exit_thread function (process.c) in Linux kernel 2.6 through 2.6.5 does not invalidate the per-TSS io_bitmap pointers if a process obta…

The exit_thread function (process.c) in Linux kernel 2.6 through 2.6.5 does not invalidate the per-TSS io_bitmap pointers if a process obtains IO access permissions from the ioperm function but does not drop those permissions when it exits, which allows other processes to access the per-TSS pointers, access restricted memory locations, and possibly gain privileges.