• [FreeBSD-Announce] FreeBSD Security Advisory FreeBSD-SA-16:38.bhyve

    From FreeBSD Security Advisories@21:1/5 to All on Tue Dec 6 20:00:01 2016
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    ============================================================================= FreeBSD-SA-16:38.bhyve Security Advisory
    The FreeBSD Project

    Topic: bhyve(8) virtual machine escape

    Category: core
    Module: bhyve
    Announced: 2016-12-06
    Credits: Felix Wilhelm
    Affects: FreeBSD 10.x, FreeBSD 11.0
    Corrected: 2016-12-06 18:54:43 UTC (stable/11, 11.0-STABLE)
    2016-12-06 18:49:38 UTC (releng/11.0, 11.0-RELEASE-p4)
    2016-12-06 18:55:01 UTC (stable/10, 10.3-STABLE)
    2016-12-06 18:49:48 UTC (releng/10.3, 10.3-RELEASE-p13)
    2016-12-06 18:49:54 UTC (releng/10.2, 10.2-RELEASE-p26)
    2016-12-06 18:49:59 UTC (releng/10.1, 10.1-RELEASE-p43)
    CVE Name: CVE-2016-1889

    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

    bhyve(8) is a hypervisor that supports running a variety of virtual
    machines (guests).

    II. Problem Description

    The bounds checking of accesses to guest memory greater than 4GB by
    device emulations is subject to integer overflow.

    III. Impact

    For a bhyve virtual machine with more than 3GB of guest memory configured,
    a malicious guest could craft device descriptors that could give it access
    to the heap of the bhyve process. Since the bhyve process is running as root, this may allow guests to obtain full control of the hosts they're running on.

    IV. Workaround

    No workaround is available, however, systems not using bhyve(8) for virtualization are not vulnerable. Additionally, systems using bhyve(8) with 3GB or less of configured guest memory are not vulnerable.

    V. Solution

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

    No reboot is needed. Rather the bhyve(8) process for vulnerable virtual machines should be restarted.

    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 amd64
    platform 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.

    [FreeBSD 11.0, FreeBSD 10.3]
    # fetch https://security.FreeBSD.org/patches/SA-16:38/bhyve.patch
    # fetch https://security.FreeBSD.org/patches/SA-16:38/bhyve.patch.asc
    # gpg --verify bhyve.patch.asc

    [FreeBSD 10.2, FreeBSD 10.1]
    # fetch https://security.FreeBSD.org/patches/SA-16:38/bhyve-10.patch
    # fetch https://security.FreeBSD.org/patches/SA-16:38/bhyve-10.patch.asc
    # gpg --verify bhyve-10.patch.asc

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

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

    Recompile the operating system using buildworld and installworld as
    described in <URL:https://www.FreeBSD.org/handbook/makeworld.html>.

    VI. Correction details

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

    Branch/path Revision
    - ------------------------------------------------------------------------- stable/10/ r309648 releng/10.1/ r309636 releng/10.2/ r309635 releng/10.3/ r309634 stable/11/ r309647 releng/11.0/ r309633
    - -------------------------------------------------------------------------

    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

    <URL:https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-1889>

    The latest revision of this advisory is available at <URL:https://security.FreeBSD.org/advisories/FreeBSD-SA-16:38.bhyve.asc> -----BEGIN PGP SIGNATURE-----

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