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FreeBSD-SA-06:25.kmem                                       Security Advisory
                                                          The FreeBSD Project

Topic:          Kernel memory disclosure in firewire(4)

Category:       core
Module:         sys_dev
Announced:      2006-12-06
Credits:        Rodrigo Rubira Branco
Affects:        All FreeBSD releases.
Corrected:      2006-12-06 09:13:51 UTC (RELENG_6, 6.2-STABLE)
                2006-12-06 09:14:23 UTC (RELENG_6_2, 6.2-RC2)
                2006-12-06 09:14:59 UTC (RELENG_6_1, 6.1-RELEASE-p11)
                2006-12-06 09:15:40 UTC (RELENG_6_0, 6.0-RELEASE-p16)
                2006-12-06 09:16:17 UTC (RELENG_5, 5.5-STABLE)
                2006-12-06 09:16:41 UTC (RELENG_5_5, 5.5-RELEASE-p9)
                2006-12-06 09:17:09 UTC (RELENG_4, 4.11-STABLE)
                2006-12-06 09:18:02 UTC (RELENG_4_11, 4.11-RELEASE-p26)
CVE Name:       CVE-2006-6013

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 firewire(4) driver provides support for IEEE 1394 ("FireWire")
interfaces.  This driver provides some of its functionality via the
ioctl(2) system call.

II.  Problem Description

In the FW_GCROM ioctl, a signed integer comparison is used instead of
an unsigned integer comparison when computing the length of a buffer
to be copied from the kernel into the calling application.

III. Impact

A user in the "operator" group can read the contents of kernel memory.
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 available, but systems without IEEE 1394 ("FireWire")
interfaces are not vulnerable.  (Note that systems with IEEE 1394
interfaces are affected regardless of whether any devices are attached.)

Note also that FreeBSD does not have any non-root users in the "operator"
group by default; systems on which no users have been added to this group
are therefore also not vulnerable.

V.   Solution

Perform one of the following:

1) Upgrade your vulnerable system to 4-STABLE, 5-STABLE, or 6-STABLE,
or to the RELENG_6_1, RELENG_6_0, RELENG_5_5, or RELENG_4_11 security
branch dated after the correction date.

2) To patch your present system:

The following patches have been verified to apply to FreeBSD 4.11, 5.5,
6.0, and 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/SA-06:25/kmem.patch
# fetch http://security.FreeBSD.org/patches/SA-06:25/kmem.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_4
  src/sys/dev/firewire/fwdev.c                                   1.2.4.17
RELENG_4_11
  src/UPDATING                                             1.73.2.91.2.27
  src/sys/conf/newvers.sh                                  1.44.2.39.2.30
  src/sys/dev/firewire/fwdev.c                               1.2.4.16.4.1
RELENG_5
  src/sys/dev/firewire/fwdev.c                                   1.44.2.2
RELENG_5_5
  src/UPDATING                                             1.342.2.35.2.9
  src/sys/conf/newvers.sh                                  1.62.2.21.2.11
  src/sys/dev/firewire/fwdev.c                               1.44.2.1.4.1
RELENG_6
  src/sys/dev/firewire/fwdev.c                                   1.46.2.2
RELENG_6_2
  src/UPDATING                                             1.416.2.29.2.1
  src/sys/dev/firewire/fwdev.c                               1.46.2.1.6.1
RELENG_6_1
  src/UPDATING                                            1.416.2.22.2.13
  src/sys/conf/newvers.sh                                  1.69.2.11.2.13
  src/sys/dev/firewire/fwdev.c                               1.46.2.1.4.1
RELENG_6_0
  src/UPDATING                                             1.416.2.3.2.21
  src/sys/conf/newvers.sh                                   1.69.2.8.2.17
  src/sys/dev/firewire/fwdev.c                               1.46.2.1.2.1
- -------------------------------------------------------------------------

VII. References

http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-6013

The latest revision of this advisory is available at
http://security.FreeBSD.org/advisories/FreeBSD-SA-06:25.kmem.asc
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