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FreeBSD i386_set_ldt Integer Overflow Vulnerability



FreeBSD is a modern operating system for x86, amd64, Alpha, IA-64, PC-98
and SPARC architectures. It's based on the UNIX operating system, BSD,
which was created at the University of California, Berkeley. More
information can be obtained from the FreeBSD Project web site at


Local exploitation of a input validation error in the FreeBSD Project's
i386_set_ldt() kernel implementation could allow attackers to create a
kernel panic, leading to a denial of service condition on the affected


Exploitation of this vulnerability would result in a denial of service
condition on the affected host. There is a potential for arbitrary code
execution in kernel context due to the way this function manipulates
kernel heap memory.


iDefense has confirmed the existence of this problem in FreeBSD 5.5. It
is suspected that versions as early as 5.2 are also affected.


iDefense is not aware of any workaround for this issue.


"It appears that the problem you have discovered was fixed in revision
1.96 of src/sys/i386/i386/sys_machdep.c on March 23, 2005, after being
found by the Coverity Prevent analysis tool; the commit message at the
time documented this as a local denial of service bug.

The policy of the FreeBSD Security Team is that local denial of service bugs
not be treated as security issues; it is possible that this problem will be
corrected in a future Erratum."


The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CVE-2006-4172 to this issue. This is a candidate for inclusion in
the CVE list (http://cve.mitre.org), which standardizes names for
security problems.


08/16/2006 Initial vendor notification
08/16/2006 Initial vendor response
09/23/2006 Public disclosure


The discoverer of this vulnerability wishes to remain anonymous.

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Copyright © 2006 Verisign, Inc.

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