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  • [FreeBSD-Announce] FreeBSD Security Advisory FreeBSD-SA-20:07.epair

    From FreeBSD Security Advisories@21:1/5 to All on Thu Mar 19 18:00:03 2020
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    ============================================================================= FreeBSD-SA-20:07.epair Security Advisory
    The FreeBSD Project

    Topic: Incorrect user-controlled pointer use in epair

    Category: core
    Module: kernel
    Announced: 2020-03-19
    Credits: Ilja van Sprundel
    Affects: All supported versions of FreeBSD.
    Corrected: 2020-02-04 04:29:54 UTC (stable/12, 12.1-STABLE)
    2020-03-19 16:50:36 UTC (releng/12.1, 12.1-RELEASE-p3)
    2020-02-04 04:29:53 UTC (stable/11, 11.3-STABLE)
    2020-03-19 16:50:36 UTC (releng/11.3, 11.3-RELEASE-p7)
    CVE Name: CVE-2020-7452

    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

    The epair(4) interface provides a pair of virtual back-to-back connected Ethernet interfaces.

    II. Problem Description

    Incorrect use of a potentially user-controlled pointer in the kernel allowed vnet jailed users to panic the system and potentially execute aribitrary code in the kernel.

    III. Impact

    Users with root level access (or the PRIV_NET_IFCREATE privilege) can panic
    the system, or potentially escape the jail or execute arbitrary code with kernel priviliges.

    IV. Workaround

    No workaround is available. Systems not using epair(4) are not vulnerable.

    V. Solution

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

    Perform one of the following:

    1) 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
    # shutdown -r +10min "Rebooting for a security update"

    2) 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 12.1]
    # fetch https://security.FreeBSD.org/patches/SA-20:07/epair.12.patch
    # fetch https://security.FreeBSD.org/patches/SA-20:07/epair.12.patch.asc
    # gpg --verify epair.12.patch.asc

    [FreeBSD 11.3]
    # fetch https://security.FreeBSD.org/patches/SA-20:07/epair.11.patch
    # fetch https://security.FreeBSD.org/patches/SA-20:07/epair.11.patch.asc
    # gpg --verify epair.11.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/12/ r357490 releng/12.1/ r359141 stable/11/ r357489 releng/11.3/ r359141
    - - -------------------------------------------------------------------------

    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-2020-7452>

    The latest revision of this advisory is available at <URL:https://security.FreeBSD.org/advisories/FreeBSD-SA-20:07.epair.asc> -----BEGIN PGP SIGNATURE-----

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