CVE Name:       CAN-2005-1400

For general information regarding FreeBSD Security Advisories,
including descriptions of the fields above, security branches, and the
following sections, please visit
<URL:http://www.freebsd.org/security/>.

I.   Background

The i386_get_ldt(2) system call allows a process to request that a
portion of its Local Descriptor Table be copied from the kernel into
userland.

II.  Problem Description

The i386_get_ldt(2) syscall performs insufficient validation of its
input arguments.  In particular, negative or very large values may
allow inappropriate data to be copied from the kernel.

III. Impact

Kernel memory may be disclosed to the user process.  Such memory might
contain sensitive information, such as portions of the file cache or
terminal buffers.  This information might be directly useful, or it
might be leveraged to obtain elevated privileges in some way.  For
example, a terminal buffer might include a user-entered password.

IV.  Workaround

No workaround is known for i386 and amd64 systems; other platforms are
not affected by this issue.

V.   Solution

Perform one of the following:

1) Upgrade your vulnerable system to 4-STABLE or 5-STABLE, or to the
RELENG_5_3, RELENG_4_11, or RELENG_4_10 security branch dated after
the correction date.

2) To patch your present system:

The following patches have been verified to apply to FreeBSD 4.10,
4.11, and 5.3 systems.

a) Download the relevant patch from the location below, and verify the
detached PGP signature using your PGP utility.

[FreeBSD 4.x]
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-05:07/ldt4.patch
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-05:07/ldt4.patch.asc

[FreeBSD 5.x]
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-05:07/ldt5.patch
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-05:07/ldt5.patch.asc

b) Apply the patch.

# cd /usr/src
# patch < /path/to/patch

c) Recompile your kernel as described in
<URL:http://www.freebsd.org/handbook/kernelconfig.html> and reboot the
system.

VI.  Correction details

The following list contains the revision numbers of each file that was
corrected in FreeBSD.

Branch                                                                                                    
                         Path                                                                            Revision
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