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  • [FreeBSD-Announce] FreeBSD Security Advisory FreeBSD-SA-20:17.usb

    From FreeBSD Security Advisories@21:1/5 to All on Tue Jun 9 18:00:00 2020
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    ============================================================================= FreeBSD-SA-20:17.usb Security Advisory
    The FreeBSD Project

    Topic: USB HID descriptor parsing error

    Category: core
    Module: kernel
    Announced: 2020-06-09
    Credits: Andy Nguyen, Google
    Affects: All supported versions of FreeBSD.
    Corrected: 2020-06-08 09:32:57 UTC (stable/12, 12.1-STABLE)
    2020-06-09 16:13:54 UTC (releng/12.1, 12.1-RELEASE-p6)
    2020-06-08 09:33:37 UTC (stable/11, 11.4-STABLE)
    2020-06-09 16:13:54 UTC (releng/11.4, 11.4-RC2-p1)
    2020-06-09 16:13:54 UTC (releng/11.3, 11.3-RELEASE-p10)
    CVE Name: CVE-2020-7456

    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

    USB Human Interface Device (HID) descriptors may push/pop the current state
    to allow description of items residing in a so-called union. FreeBSD
    supports 4 such pop levels.

    II. Problem Description

    If the push/pop level is not restored within the processing of the same HID item, an invalid memory location may be used for subsequent HID item processing.

    III. Impact

    An attacker with physical access to a USB port may be able to use a specially crafted USB device to gain kernel or user-space code execution.

    IV. Workaround

    Setting "sysctl hw.usb.disable_enumeration=1" disables USB device
    enumeration preventing the error from occurring.

    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-20:17/usb.patch
    # fetch https://security.FreeBSD.org/patches/SA-20:17/usb.patch.asc
    # gpg --verify usb.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/ r361918 releng/12.1/ r361972 stable/11/ r361919 releng/11.4/ r361972 releng/11.3/ r361972
    - -------------------------------------------------------------------------

    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-2020-7456>

    The latest revision of this advisory is available at <URL:https://security.FreeBSD.org/advisories/FreeBSD-SA-20:17.usb.asc> -----BEGIN PGP SIGNATURE-----

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