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  • [FreeBSD-Announce] FreeBSD Errata Notice FreeBSD-EN-21:03.vnet

    From FreeBSD Errata Notices@21:1/5 to All on Fri Jan 29 03:00:01 2021
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    ============================================================================= FreeBSD-EN-21:03.vnet Errata Notice
    The FreeBSD Project

    Topic: Panic when destroying VNET and epair simultaneously

    Category: core
    Module: kernel
    Announced: 2021-01-29
    Affects: FreeBSD 12.1 and later.
    Corrected: 2020-12-15 15:33:28 UTC (stable/12, 12.2-STABLE)
    2021-01-29 01:20:52 UTC (releng/12.2, 12.2-RELEASE-p3)
    2021-01-29 01:06:03 UTC (releng/12.1, 12.1-RELEASE-p13)

    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

    VNET permits systems to be configured with multiple instances of the in-kernel network stack.

    The epair(4) interface provides a pair of virtual back-to-back connected Ethernet interfaces.

    II. Problem Description

    Insufficient locking in the kernel meant that destroying an epair and a vnet jail at the same time often resulted in panics.

    III. Impact

    Users with root level access (or the PRIV_NET_IFCREATE privilege) can panic
    the system.

    IV. Workaround

    The panic can be avoided by ensuring that epair interfaces are fully destroyed before the vnet jails containing them are destroyed.

    Systems not using vnet jails are not affected.

    V. Solution

    Upgrade your 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 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 an errata update"

    2) 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.

    # fetch https://security.FreeBSD.org/patches/EN-21:03/vnet.patch
    # fetch https://security.FreeBSD.org/patches/EN-21:03/vnet.patch.asc
    # gpg --verify vnet.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/ r368663 releng/12.2/ r369172 releng/12.1/ r369163
    - -------------------------------------------------------------------------

    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://bugs.freebsd.org/bugzilla/show_bug.cgi?id=238870>

    The latest revision of this advisory is available at <URL:https://security.FreeBSD.org/advisories/FreeBSD-EN-21:03.vnet.asc> -----BEGIN PGP SIGNATURE-----

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