[FreeBSD-Announce] FreeBSD Errata Notice FreeBSD-EN-14:06.exec

FreeBSD Errata Notices errata-notices at freebsd.org
Tue Jun 3 19:34:12 UTC 2014

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FreeBSD-EN-14:06.exec                                           Errata Notice
                                                          The FreeBSD Project

Topic:          triple-fault when executing from a threaded process

Category:       core
Module:         kern
Announced:      2014-06-03
Credits:        Ivo De Decker and Debian GNU/kFreeBSD porters
Affects:        All supported versions of FreeBSD.
Corrected:      2014-05-23 09:29:04 UTC (stable/10, 10.0-STABLE)
                2014-06-03 19:02:52 UTC (releng/10.0, 10.0-RELEASE-p4)
                2014-05-23 11:56:32 UTC (stable/9, 9.2-STABLE)
                2014-06-03 19:03:11 UTC (releng/9.2, 9.2-RELEASE-p7)
                2014-06-03 19:03:11 UTC (releng/9.1, 9.1-RELEASE-p14)
                2014-05-23 09:48:42 UTC (stable/8, 8.4-STABLE)
                2014-06-03 19:03:23 UTC (releng/8.4, 8.4-RELEASE-p11)
CVE Name:       CVE-2014-3880

For general information regarding FreeBSD Errata Notices and Security
Advisories, including descriptions of the fields above, security
branches, and the following sections, please visit

I.   Background

The execve and fexecve system calls transforms the calling process into a
new process, constructed from an ordinarty file.

When executing a new process, the FreeBSD virtual memory subsystem tries to
optimize the process by avoiding destroying the old virtual memory address
space when the calling process do not share its address space with another
process (for instance, via rfork(2) with RFMEM) and when the new min/max
address limit stays the same.  In the optimized scenario, the virtual memory
subsystem only removes usermode mappings from the existing virtual memory
address space instead of destroying and recreating it.

II.  Problem Description

When the virtual memory address space is recreated for the calling process,
the old virtual memory address space as well as its associated mappings are
destroyed before thread_single(9) boundary, where threads were allowed to
run to safely terminate.  If such threads were on other CPUs, the old page
table pointer may still be referenced.

III. Impact

The system will crash when this happens due to a triple-fault triggered by
dereferencing an invalid page table pointer.

IV.  Workaround

No workaround is available, but systems that do not run binaries that are
of different bit-ness (e.g. 32-bit and 64-bit binaries) are not affected.

V.   Solution

Perform one of the following:

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

2) To update your present 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.

[FreeBSD 8.4]
# fetch http://security.FreeBSD.org/patches/EN-14:06/exec-8.4.patch
# fetch http://security.FreeBSD.org/patches/EN-14:06/exec-8.4.patch.asc
# gpg --verify exec-8.4.patch.asc

[FreeBSD 9.1]
# fetch http://security.FreeBSD.org/patches/EN-14:06/exec-9.1.patch
# fetch http://security.FreeBSD.org/patches/EN-14:06/exec-9.1.patch.asc
# gpg --verify exec-9.1.patch.asc

[FreeBSD 9.2]
# fetch http://security.FreeBSD.org/patches/EN-14:06/exec-9.2.patch
# fetch http://security.FreeBSD.org/patches/EN-14:06/exec-9.2.patch.asc
# gpg --verify exec-9.2.patch.asc

[FreeBSD 10.0]
# fetch http://security.FreeBSD.org/patches/EN-14:06/exec-10.0.patch
# fetch http://security.FreeBSD.org/patches/EN-14:06/exec-10.0.patch.asc
# gpg --verify exec-10.0.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:http://www.FreeBSD.org/handbook/kernelconfig.html> and reboot the

3) To update your 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

VI.  Correction details

The following list contains the revision numbers of each file that was
corrected in FreeBSD.

Branch/path                                                      Revision
- -------------------------------------------------------------------------
stable/8/                                                         r266583
releng/8.4/                                                       r267019
stable/9/                                                         r266585
releng/9.1/                                                       r267018
releng/9.2/                                                       r267018
stable/10/                                                        r266582
releng/10.0/                                                      r267017
- -------------------------------------------------------------------------

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:


VII. References



The latest revision of this Errata Notice is available at

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