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  • [FreeBSD-Announce] FreeBSD Errata Notice FreeBSD-EN-18:10.syscall

    From FreeBSD Errata Notices@21:1/5 to All on Thu Sep 27 21:00:01 2018
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    ============================================================================= FreeBSD-EN-18:10.syscall Errata Notice
    The FreeBSD Project

    Topic: NULL pointer dereference in freebsd4_getfsstat system call

    Category: core
    Module: kernel
    Announced: 2018-09-27
    Credits: Thomas Barabosch, Fraunhofer FKIE
    Affects: FreeBSD 11.x
    Corrected: 2018-09-27 18:54:41 UTC (stable/11, 11.1-STABLE)
    2018-09-27 18:32:14 UTC (releng/11.2, 11.2-RELEASE-p4)
    2018-09-27 18:32:14 UTC (releng/11.1, 11.1-RELEASE-p15)
    CVE Name: CVE-2018-17154

    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 freebsd4_getfsstat system call returns information about all mounted file systems in a binary format compatible with FreeBSD 4.x. Part of the call includes passing in a userland allocated buffer for the system call to fill along with the size of the buffer.

    II. Problem Description

    Insufficient checking occurs on the buffer when a very large buffer size causes memory allocation to fail. Resulting code attempts to free the NULL pointer.

    III. Impact

    A local unprivileged user may cause a denial of service using a specially crafted binary.

    IV. Workaround

    No workaround is available.

    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.x]
    # fetch https://security.FreeBSD.org/patches/EN-18:10/syscall-11.patch
    # fetch https://security.FreeBSD.org/patches/EN-18:10/syscall-11.patch.asc
    # gpg --verify syscall-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/11/ r338987 releng/11.1/ r338979 releng/11.2/ r338979
    - -------------------------------------------------------------------------

    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-2018-17154>

    The latest revision of this advisory is available at <URL:https://security.FreeBSD.org/advisories/FreeBSD-EN-18:10.syscall.asc> -----BEGIN PGP SIGNATURE-----

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