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  • [FreeBSD-Announce] FreeBSD Errata Notice FreeBSD-EN-18:15.loader

    From FreeBSD Errata Notices@21:1/5 to All on Tue Nov 27 22:00:01 2018
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    ============================================================================= FreeBSD-EN-18:15.loader Errata Notice
    The FreeBSD Project

    Topic: Deferred kernel loading breaks loader password

    Category: core
    Module: loader
    Announced: 2018-11-27
    Credits: Devin Teske
    Affects: All supported versions of FreeBSD.
    Corrected: 2018-10-24 23:17:17 UTC (stable/11, 11.2-STABLE)
    2018-11-27 19:45:25 UTC (releng/11.2, 11.2-RELEASE-p5)

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

    I. Background

    The loader is a FreeBSD component which is part of the boot sequence for a machine. The loader is most commonly visible with the "beastie" boot menu, allowing specification of different boot time parameters.

    II. Problem Description

    A change in the loader to allow deferred loading of the kernel introduced a
    bug when using a loader password. After this change and when the loader password is enabled, the menu is not loaded and instead the machine goes into the autoboot routine. The autoboot routine then fails when the kernel has
    not yet been loaded, yielding a loader prompt where the user has full control of the boot process.

    III. Impact

    Setting the loader password with the intention of preventing the user from bypassing the boot process instead causes the boot to fail and gives the user full control of the boot process.

    IV. Workaround

    No workaround is available, but systems that do not use a loader password are not vulnerable.

    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.

    Afterward, reboot the system.

    2) 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

    Afterward, reboot the system.

    3) To update your 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 11.2]
    # fetch https://security.FreeBSD.org/patches/EN-18:15/loader.patch
    # fetch https://security.FreeBSD.org/patches/EN-18:15/loader.patch.asc
    # gpg --verify loader.patch.asc

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

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

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

    VI. Correction details

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

    Branch/path Revision
    - ------------------------------------------------------------------------- stable/11/ r339697 releng/11.2/ r341093
    - -------------------------------------------------------------------------

    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

    The latest revision of this advisory is available at <URL:https://security.FreeBSD.org/advisories/FreeBSD-EN-18:15.loader.asc> -----BEGIN PGP SIGNATURE-----

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