Potential localhost root hole

In July of 1998 the OpenBSD kernel was modified to populate file
descriptors 0-2 on exec for setuid (and setgid) processes.  This
was done to defeat an attack on setuid programs that open files for
writing and also write to descriptors 0-2 (usually via stdin, stdout
or stderr).

The fix at that time didn't properly deal with the possibility that
the allocation of the dummy descriptors could fail due to a full
file descriptor table.  It has come to our attention that there is
a winnable race condition when the file descriptor table is full,
allowing an fd 0-2 attack to succeed.

Credit for finding this goes to FozZy of Hackademy / Hackerz Voice.
Please see his advisory on bugtraq for more in-depth details.

The following patches are available:

OpenBSD-3.1:
    ftp://ftp.openbsd.org/pub/OpenBSD/patches/3.1/common/003_fdalloc2.patch

OpenBSD-3.0:
    ftp://ftp.openbsd.org/pub/OpenBSD/patches/3.0/common/021_fdalloc2.patch

OpenBSD-2.9:
    ftp://ftp.openbsd.org/pub/OpenBSD/patches/2.9/common/026_fdalloc2.patch

OpenBSD-current as well as the OpenBSD 2.9, 3.0 and 3.1 -stable
branches have already been patched.