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  • [FreeBSD-Announce] FreeBSD Security Advisory FreeBSD-SA-20:20.ipv6

    From FreeBSD Security Advisories@21:1/5 to All on Wed Jul 8 22:00:02 2020
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    ============================================================================= FreeBSD-SA-20:20.ipv6 Security Advisory
    The FreeBSD Project

    Topic: IPv6 socket option race condition and use after free

    Category: core
    Module: network
    Announced: 2020-07-08
    Credits: syzkaller, Andy Nguyen
    Affects: All supported versions of FreeBSD.
    Corrected: 2020-04-02 15:30:51 UTC (stable/12, 12.1-STABLE)
    2020-07-08 20:11:40 UTC (releng/12.1, 12.1-RELEASE-p7)
    2020-07-06 20:23:14 UTC (stable/11, 11.4-STABLE)
    2020-07-08 20:11:40 UTC (releng/11.4, 11.4-RELEASE-p1)
    2020-07-08 20:11:40 UTC (releng/11.3, 11.3-RELEASE-p11)
    CVE Name: CVE-2020-7457

    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 IPV6_2292PKTOPTIONS socket option allows user code to set IPv6
    header options on a socket.

    II. Problem Description

    The IPV6_2292PKTOPTIONS set handler was missing synchronization,
    so racing accesses could modify freed memory.

    III. Impact

    A malicious user application could trigger memory corruption, leading
    to privilege escalation.

    IV. Workaround

    No workaround is available.

    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-20:20/ipv6.patch
    # fetch https://security.FreeBSD.org/patches/SA-20:20/ipv6.patch.asc
    # gpg --verify ipv6.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/ r359565 releng/12.1/ r363026 stable/11/ r362975 releng/11.4/ r363026 releng/11.3/ r363026
    - -------------------------------------------------------------------------

    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://hackerone.com/reports/826026>

    <URL:https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-7457>

    The latest revision of this advisory is available at <URL:https://security.FreeBSD.org/advisories/FreeBSD-SA-20:20.ipv6.asc> -----BEGIN PGP SIGNATURE-----

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