FreeBSD: cvs Heap overflow vulnerability
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FreeBSD Malformed data can cause a heap buffer to overflow, allowing the client to overwrite arbitrary portions of the server's memory.

FreeBSD-SA-04:10.cvs                                        Security Advisory
                                                          The FreeBSD Project

Topic:          CVS pserver protocol parser errors

Category:       contrib
Module:         contrib_cvs
Announced:      2004-05-19
Credits:        Stefan Esser <s.esser@e-matters.de>
Affects:        All FreeBSD versions
Corrected:      2004-05-18 07:21:57 UTC (RELENG_4, 4.10-PRERELEASE)
                2004-05-18 07:16:53 UTC (RELENG_4_10, 4.10-RC)
                2004-05-18 07:19:55 UTC (RELENG_4_9, 4.9-RELEASE-p8)
                2004-05-18 07:19:55 UTC (RELENG_4_8, 4.8-RELEASE-p21)
                2004-05-18 07:19:54 UTC (RELENG_4_7, 4.7-RELEASE-p27)
                2004-05-18 07:19:57 UTC (RELENG_5_2, 5.2.1-RELEASE-p7)
                2004-05-18 07:19:57 UTC (RELENG_5_1, 5.1-RELEASE-p17)
                2004-05-18 07:19:56 UTC (RELENG_5_0, 5.0-RELEASE-p21)
CVE Name:       CAN-2004-0396
FreeBSD only:   NO

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

I.   Background

The Concurrent Versions System (CVS) is a version control system.  It
may be used to access a repository locally, or to access a `remote
repository' using a number of different methods.  When accessing a
remote repository, the target machine runs the CVS server to fulfill
client requests.

II.  Problem Description

Due to a programming error in code used to parse data received from
the client, malformed data can cause a heap buffer to overflow,
allowing the client to overwrite arbitrary portions of the server's
memory.

III. Impact

A malicious CVS client may run arbitrary code on the server at the
privilege level of the CVS server software.

IV.  Workaround

Administrators of CVS repositories should disable remote access
through the "pserver" mechanism.  CVS servers which only allow remote
access through the "ext" mechanism (using RSH or SSH) are not
affected.

V.   Solution

Perform one of the following:

1) Upgrade your vulnerable system to 4-STABLE; or to the RELENG_5_2,
RELENG_4_9, or RELENG_4_8 security branch dated after the correction
date.

2) To patch your present system:

The following patches have been verified to apply to FreeBSD 4.7, 4.8,
4.9, 4.10, 5.0, 5.1, and 5.2 systems.

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

# fetch  ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-04:10/cvs.patch
# fetch  ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-04:10/cvs.patch.asc

b) Execute the following commands as root:

# cd /usr/src
# patch < /path/to/patch
# cd /usr/src/gnu/usr.bin/cvs
# 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_4
  src/contrib/cvs/src/server.c                                   1.13.2.6
RELENG_4_10
  src/contrib/cvs/src/server.c                               1.13.2.5.6.1
RELENG_4_9
  src/UPDATING                                              1.73.2.89.2.9
  src/sys/conf/newvers.sh                                   1.44.2.32.2.9
  src/contrib/cvs/src/server.c                               1.13.2.5.4.1
RELENG_4_8
  src/UPDATING                                             1.73.2.80.2.24
  src/sys/conf/newvers.sh                                  1.44.2.29.2.22
  src/contrib/cvs/src/server.c                               1.13.2.5.2.1
RELENG_4_7
  src/UPDATING                                             1.73.2.74.2.31
  src/sys/conf/newvers.sh                                  1.44.2.26.2.29
  src/contrib/cvs/src/server.c                               1.13.2.2.6.2
RELENG_5_2
  src/UPDATING                                                 1.282.2.15
  src/sys/conf/newvers.sh                                       1.56.2.14
  src/contrib/cvs/src/server.c                                   1.19.4.2
RELENG_5_1
  src/UPDATING                                                 1.251.2.19
  src/sys/conf/newvers.sh                                       1.50.2.19
  src/contrib/cvs/src/server.c                                   1.19.2.1
RELENG_5_0
  src/UPDATING                                                 1.229.2.27
  src/sys/conf/newvers.sh                                       1.48.2.22
  src/contrib/cvs/src/server.c                                   1.17.2.2
- - -------------------------------------------------------------------------

VII. References
 
http://ccvs.cvshome.org/servlets/NewsItemView?newsID=104