1. Forum
  2. Usenet
  3. COMP.UNIX.BSD.FREEBSD.ANN

  • [FreeBSD-Announce] FreeBSD Security Advisory FreeBSD-SA-20:08.jail

    From FreeBSD Security Advisories@21:1/5 to All on Thu Mar 19 18:00:03 2020
    -----BEGIN PGP SIGNED MESSAGE-----
    Hash: SHA512

    ============================================================================= FreeBSD-SA-20:08.jail Security Advisory
    The FreeBSD Project

    Topic: Kernel memory disclosure with nested jails

    Category: core
    Module: kern
    Announced: 2020-03-19
    Credits: Hans Christian Woithe <chwoithe@yahoo.com>
    Affects: All supported versions of FreeBSD.
    Corrected: 2020-03-16 21:12:46 UTC (stable/12, 12.1-STABLE)
    2020-03-19 16:51:33 UTC (releng/12.1, 12.1-RELEASE-p3)
    2020-03-16 21:12:32 UTC (stable/11, 11.3-STABLE)
    2020-03-19 16:51:33 UTC (releng/11.3, 11.3-RELEASE-p7)
    CVE Name: CVE-2020-7453

    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 jail_set(2) system call allows a system administrator to lock up a
    process and all its descendants inside a closed environment with very
    limited ability to affect the system outside that environment, even
    for processes with superuser privileges.

    The jail_get(2) system call allows a system administrator to read the configuration of running jails.

    II. Problem Description

    A missing NUL-termination check for the jail_set(2) configration option "osrelease" may return more bytes when reading the jail configuration
    back with jail_get(2) than were originally set.

    III. Impact

    For jails with a non-default setting of children.max > 0 ("nested jails")
    a superuser inside a jail can create a jail and may be able to read and
    take advantage of exposed kernel memory.

    IV. Workaround

    No workaround is available. Systems not altering the default settings of
    the jail configuration option children.max=0 are not affected as a root on
    the base system has access to kernel memory by other means and a super
    user inside a jail cannot create further jails.

    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.

    # fetch https://security.FreeBSD.org/patches/SA-20:08/kern_jail.patch
    # fetch https://security.FreeBSD.org/patches/SA-20:08/kern_jail.patch.asc
    # gpg --verify kern_jail.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/ r359021 releng/12.1/ r359142 stable/11/ r359020 releng/11.3/ r359142
    - -------------------------------------------------------------------------

    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-2020-7453>

    The latest revision of this advisory is available at <URL:https://security.FreeBSD.org/advisories/FreeBSD-SA-20:08.jail.asc> -----BEGIN PGP SIGNATURE-----

    iQKTBAEBCgB9FiEE/A6HiuWv54gCjWNV05eS9J6n5cIFAl5zplhfFIAAAAAALgAo aXNzdWVyLWZwckBub3RhdGlvbnMub3BlbnBncC5maWZ0aGhvcnNlbWFuLm5ldEZD MEU4NzhBRTVBRkU3ODgwMjhENjM1NUQzOTc5MkY0OUVBN0U1QzIACgkQ05eS9J6n 5cKWdw//ZFfaoCenbVtvB6a4JW9HOT0yMoDXup+OdpjbhUTsJSyvDB9eZUSiZJ7u 4rQZpYQZotND2I/U8BSUjcJlDVzhTn6WN1yZFpWI9oFrSJhKxkwGMuetocUw7MgE ++WaaVueodMBjG7+v7mUmr5pXomdpxCO4XZxTW0BCm3Pvydera1kZVHzQ2pAw0On cnOiSN+v04latfkjjdjPv+oC8GUsI3Q+4jF745MN9dND+4KV/4CW5BJg6sUiJakx WB6cXayxp+Q/WPoB4OS/w3loe1FGIqESjXMxdHAV0n9eVofv8+h0rQt5kQ9oFpCm Ql2NUG7xKqoidGlhzff5w0j5+VNXA/exv+sH/lQTZO5xJa/5Ti1wlUxsrp/8jO9Z vRDd3CwjOIG+dFBSAXWcAaSedJ+Ax97RVbfKmYiy5B7ujJp/X6rJXU2G3zOhObCS 8/E+KHlj9YT4hN73zDeGiw5zKVjbfVQp661mKgP1lO+4Mv9357F8epux+CV3fdb6 BBttCm8l8ubhfr12fmBAfXUXDx7stNTpvcgphGUB0v6Sfxbv0OHoGzfAGrQ3i3LP Os7OoFRJ+2SJ/G8xpjVjriOsAoLeUX43JIlPTOEvU2mhol/M717Rwn94ndqXfNJh XCF2AaOVXxBpdx2Vik3FBTGZvAfTCxMQOZwGn7zVzpbxlCbasKM=
    =13XM
    -----END PGP SIGNATURE-----
    _______________________________________________
    freebsd-announce@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-announce
    To unsubscribe, send any mail to "freebsd-announce-unsubscribe@freebsd.org"

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)