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FreeBSD-SA-15:02.kmem                                       Security Advisory
                                                          The FreeBSD Project

Topic:          SCTP SCTP_SS_VALUE kernel memory corruption and disclosure

Category:       core
Module:         sctp
Announced:      2015-01-27
Credits:        Clement LECIGNE from Google Security Team and
                Francisco Falcon from Core Security Technologies
Affects:        All supported versions of FreeBSD.
Corrected:      2015-01-27 19:36:08 UTC (stable/10, 10.1-STABLE)
                2015-01-27 19:37:02 UTC (releng/10.1, 10.1-RELEASE-p5)
                2015-01-27 19:37:02 UTC (releng/10.0, 10.0-RELEASE-p17)
                2015-01-27 19:36:08 UTC (stable/9, 9.3-STABLE)
                2015-01-27 19:37:02 UTC (releng/9.3, 9.3-RELEASE-p9)
                2015-01-27 19:36:08 UTC (stable/8, 8.4-STABLE)
                2015-01-27 19:37:02 UTC (releng/8.4, 8.4-RELEASE-p23)
CVE Name:       CVE-2014-8612

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

I.   Background

SCTP protocol provides reliable, flow-controlled, two-way transmission
of data.  It is a message oriented protocol and can support the SOCK_STREAM
and SOCK_SEQPACKET abstractions.

SCTP allows the user to choose between multiple scheduling algorithms to
optimize the sending behavior of SCTP in scenarios with different
requirements.

II.  Problem Description

Due to insufficient validation of the SCTP stream ID, which serves as an array
index, a local unprivileged attacker can read or write 16-bits of kernel
memory.

III. Impact

An unprivileged process can read or modify 16-bits of memory which
belongs to the kernel.  This smay lead to exposure of sensitive
information or allow privilege escalation.

IV.  Workaround

No workaround is available.

V.   Solution

Perform one of the following:

1) Upgrade your vulnerable system to a supported FreeBSD stable or
release / security branch (releng) dated after the correction date.

2) To update your vulnerable system via a binary patch:

Systems running a RELEASE version of FreeBSD on the i386 or amd64
platforms can be updated via the freebsd-update(8) utility:

# freebsd-update fetch
# freebsd-update install

3) To update your vulnerable system via a source code patch:

The following patches have been verified to apply to the applicable
FreeBSD release branches.

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

# fetch https://security.FreeBSD.org/patches/SA-15:02/sctp.patch
# fetch https://security.FreeBSD.org/patches/SA-15:02/sctp.patch.asc
# gpg --verify sctp.patch.asc

b) Apply the patch.  Execute the following commands as root:

# cd /usr/src
# patch < /path/to/patch

c) Recompile your kernel as described in
<URL:https://www.FreeBSD.org/handbook/kernelconfig.html> and reboot the
system.

VI.  Correction details

The following list contains the correction revision numbers for each
affected branch.

Branch/path                                                      Revision
- -------------------------------------------------------------------------
stable/8/                                                         r277807
releng/8.4/                                                       r277808
stable/9/                                                         r277807
releng/9.3/                                                       r277808
stable/10/                                                        r277807
releng/10.0/                                                      r277808
releng/10.1/                                                      r277808
- -------------------------------------------------------------------------

To see which files were modified by a particular revision, run the
following command, replacing NNNNNN with the revision number, on a
machine with Subversion installed:

# svn diff -cNNNNNN --summarize svn://svn.freebsd.org/base

Or visit the following URL, replacing NNNNNN with the revision number:

<URL:https://svnweb.freebsd.org/base?view=revision&revision=NNNNNN>

VII. References

We would like to acknowledge Clement LECIGNE from Google Security Team and
Francisco Falcon from Core Security Technologies who discovered the issue
independently and reported to the FreeBSD Security Team.

<URL:http://www.coresecurity.com/content/freebsd-kernel-multiple-vulnerabilities>

<URL:https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2014-8612>

The latest revision of this advisory is available at
<URL:https://security.FreeBSD.org/advisories/FreeBSD-SA-15:02.kmem.asc>
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