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FreeBSD-EN-06:02.net                                            Errata Notice
                                                          The FreeBSD Project

Topic:          Networking Issues

Category:       core
Module:         sys
Announced:      2006-08-28
Credits:        Robert Watson, JINMEI Tatuya
Affects:        FreeBSD 6.1-RELEASE
Corrected:      2006-08-28 07:31:11 UTC (RELENG_6_1, 6.1-RELEASE-p5)

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

I.   Background

The FreeBSD kernel provides basic networking services, supporting the
IPv4 and IPv6 network protocols.

II.  Problem Description

Several issues have been discovered in the networking code in the
FreeBSD 6.1 kernel.  Specifically:

1.  A pointer was not being checked for validity before being
    dereferenced.

2.  Some statistics-keeping code in the UMA memory allocator
    erroneously counted certain types of successful memory allocations
    as failures.

3.  IPv6 neighbor discovery did not work correctly over point-to-point
    links.

III. Impact

The impacts of these bugs are varied.

1.  The pointer dereferencing issue could cause a kernel panic.

2.  The memory statistics-keeping error could cause the kernel to
    report an incorrect number of memory allocations that failed.
    One symptom of this problem is a artificially high count of
    "requests for mbufs denied" in the output from "netstat -m".

3.  The IPv6 neighbor discovery bug could cause spurious warnings to
    be generated when running IPv6 over point-to-point links.  This
    problem was particularly noticeable over gif(4) tunnels.

IV.  Workaround

No workaround is available.

V.   Solution

Perform one of the following:

1) Upgrade your vulnerable system to 6-STABLE, or to the RELENG_6_1
security branch dated after the correction date.

2) To patch your present system:

The following patch has been verified to apply to FreeBSD 6.1 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/EN-06:02/net.patch
# fetch http://security.FreeBSD.org/patches/EN-06:02/net.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                                                           Revision
  Path
- -------------------------------------------------------------------------
RELENG_6_1
  src/UPDATING                                             1.416.2.22.2.7
  src/sys/conf/newvers.sh                                   1.69.2.11.2.7
  src/sys/netinet/ip_output.c                               1.242.2.8.2.1
  src/sys/netinet6/in6.c                                     1.51.2.8.2.1
  src/sys/netinet6/nd6.c                                    1.48.2.12.2.1
  src/sys/vm/uma_core.c                                    1.119.2.15.2.1
- -------------------------------------------------------------------------

The latest revision of this advisory is available at
http://security.FreeBSD.org/advisories/FreeBSD-EN-06:02.net.asc
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