139 lines
5.2 KiB
Text
139 lines
5.2 KiB
Text
-----BEGIN PGP SIGNED MESSAGE-----
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Hash: SHA512
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=============================================================================
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FreeBSD-SA-16:18.atkbd Security Advisory
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The FreeBSD Project
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Topic: Buffer overflow in keyboard driver
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Category: core
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Module: atkbd
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Announced: 2016-05-17
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Credits: CTurt and the HardenedBSD team
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Affects: All supported versions of FreeBSD.
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Corrected: 2016-05-17 22:29:59 UTC (stable/10, 10.3-STABLE)
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2016-05-17 22:28:27 UTC (releng/10.3, 10.3-RELEASE-p3)
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2016-05-17 22:28:20 UTC (releng/10.2, 10.2-RELEASE-p17)
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2016-05-17 22:28:11 UTC (releng/10.1, 10.1-RELEASE-p34)
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2016-05-17 22:31:12 UTC (stable/9, 9.3-STABLE)
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2016-05-17 22:28:36 UTC (releng/9.3, 9.3-RELEASE-p42)
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CVE Name: CVE-2016-1886
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For general information regarding FreeBSD Security Advisories,
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including descriptions of the fields above, security branches, and the
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following sections, please visit <URL:https://security.FreeBSD.org/>.
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I. Background
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The atkbd(4) driver, together with the atkbdc(4) driver, provides access
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to the AT 84 keyboard or the AT enhanced keyboard which is connected to
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the AT keyboard controller. The driver is required for the console driver
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syscons(4) or vt(4). The driver exposes its own ioctl(2) interface to allow
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it to be configured from userland through the kbdcontrol(1) utility.
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II. Problem Description
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Incorrect signedness comparison in the ioctl(2) handler allows a malicious
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local user to overwrite a portion of the kernel memory.
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III. Impact
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A local user may crash the kernel, read a portion of kernel memory and
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execute arbitrary code in kernel context. The result of executing an
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arbitrary kernel code is privilege escalation.
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IV. Workaround
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Disallow keymap changes for non-privileged users:
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sysctl hw.kbd.keymap_restrict_change=4
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V. Solution
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Perform one of the following:
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1) Upgrade your vulnerable system to a supported FreeBSD stable or
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release / security branch (releng) dated after the correction date.
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Reboot is required.
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2) To update your vulnerable system via a binary patch:
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Systems running a RELEASE version of FreeBSD on the i386 or amd64
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platforms can be updated via the freebsd-update(8) utility:
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# freebsd-update fetch
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# freebsd-update install
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Reboot is required.
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3) To update your vulnerable system via a source code patch:
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The following patches have been verified to apply to the applicable
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FreeBSD release branches.
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a) Download the relevant patch from the location below, and verify the
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detached PGP signature using your PGP utility.
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# fetch https://security.FreeBSD.org/patches/SA-16:18/atkbd.patch
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# fetch https://security.FreeBSD.org/patches/SA-16:18/atkbd.patch.asc
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# gpg --verify atkbd.patch.asc
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b) Apply the patch. Execute the following commands as root:
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# cd /usr/src
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# patch < /path/to/patch
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c) Recompile your kernel as described in
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<URL:https://www.FreeBSD.org/handbook/kernelconfig.html> and reboot the
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system.
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VI. Correction details
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The following list contains the correction revision numbers for each
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affected branch.
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Branch/path Revision
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- -------------------------------------------------------------------------
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stable/9/ r300093
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releng/9.3/ r300088
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stable/10/ r300091
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releng/10.1/ r300085
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releng/10.2/ r300086
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releng/10.3/ r300087
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- -------------------------------------------------------------------------
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To see which files were modified by a particular revision, run the
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following command, replacing NNNNNN with the revision number, on a
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machine with Subversion installed:
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# svn diff -cNNNNNN --summarize svn://svn.freebsd.org/base
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Or visit the following URL, replacing NNNNNN with the revision number:
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<URL:https://svnweb.freebsd.org/base?view=revision&revision=NNNNNN>
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VII. References
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<URL:http://cturt.github.io/SETFKEY.html>
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<URL:https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-1886>
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The latest revision of this advisory is available at
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<URL:https://security.FreeBSD.org/advisories/FreeBSD-SA-16:18.atkbd.asc>
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