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FreeBSD-SA-06:24.libarchive                                 Security Advisory
                                                          The FreeBSD Project

Topic:          Infinite loop in corrupt archives handling in libarchive(3)

Category:       core
Module:         libarchive
Announced:      2006-11-08
Credits:        Rink Springer
Affects:        FreeBSD 6-STABLE after 2006-09-05 05:23:51 UTC
Corrected:      2006-11-08 14:05:40 UTC (RELENG_6, 6.2-RC1)
CVE Name:       CVE-2006-5680

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

I.   Background

The libarchive library provides a flexible interface for reading and
writing streaming archive files such as tar and cpio, and has been the
basis for FreeBSD's implementation of the tar(1) utility since FreeBSD 5.3.

II.  Problem Description

If the end of an archive is reached while attempting to "skip" past a
region of an archive, libarchive will enter an infinite loop wherein it
repeatedly attempts (and fails) to read further data.

III. Impact

An attacker able to cause a system to extract (via "tar -x" or another
application which uses libarchive) or list the contents (via "tar -t" or
another libarchive-using application) of an archive provided by the
attacker can cause libarchive to enter an infinite loop and use all
available CPU time.

IV.  Workaround

No workaround is available.

V.   Solution

Perform one of the following:

1) Upgrade your vulnerable system to 6-STABLE dated after the correction
date.

2) To patch your present system:

The following patches have been verified to apply to affected systems.

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

# fetch http://security.FreeBSD.org/patches/SA-06:24/libarchive.patch
# fetch http://security.FreeBSD.org/patches/SA-06:24/libarchive.patch.asc

b) Execute the following commands as root:

# cd /usr/src
# patch < /path/to/patch
# cd /usr/src/lib/libarchive
# make obj && make depend && make && make install

VI.  Correction details

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

Branch                                                           Revision
  Path
- -------------------------------------------------------------------------
RELENG_6
  src/lib/libarchive/archive_read_support_compression_none.c      1.6.2.2
- -------------------------------------------------------------------------

VII. References

http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-5680

The latest revision of this advisory is available at
http://security.FreeBSD.org/advisories/FreeBSD-SA-06:24.libarchive.asc
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