131 lines
5 KiB
Text
131 lines
5 KiB
Text
-----BEGIN PGP SIGNED MESSAGE-----
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Hash: SHA512
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=============================================================================
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FreeBSD-EN-20:02.nmount Errata Notice
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The FreeBSD Project
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Topic: nmount invalid pointer dereference
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Category: core
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Module: kernel
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Announced: 2020-01-28
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Credits: Andrew Turner
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Affects: FreeBSD 11.3 and FreeBSD 12.0.
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Corrected: 2019-10-03 07:17:26 UTC (stable/12, 12.1-STABLE)
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2019-10-04 14:10:56 UTC (releng/12.1, 12.1-RELEASE)
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2020-01-28 18:54:15 UTC (releng/12.0, 12.0-RELEASE-p13)
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2019-10-04 17:27:49 UTC (stable/11, 11.3-STABLE)
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2020-01-28 18:54:15 UTC (releng/11.3, 11.3-RELEASE-p6)
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For general information regarding FreeBSD Errata Notices and Security
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Advisories, including descriptions of the fields above, security
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branches, and the following sections, please visit
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<URL:https://security.FreeBSD.org/>.
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I. Background
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The nmount(2) system call is used to mount file systems.
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II. Problem Description
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VFS option processing related to the nmount(2) system call was missing a
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length check. This is generally only available to privileged users unless
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the vfs.usermount sysctl is changed from the default to allow non-privileged
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users the ability to mount file systems.
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III. Impact
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A userland process authorized to mount filesystems can possibly trigger a
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kernel panic.
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IV. Workaround
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No workaround is available. However, if the vfs.usermount sysctl has been
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changed to allow non-privileged users the ability to mount file systems,
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switching back to the default value of 0 will prevent non-privileged users
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from triggering the issue.
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V. Solution
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Upgrade your system to a supported FreeBSD stable or release / security
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branch (releng) dated after the correction date, and reboot.
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Perform one of the following:
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1) To update your system via a binary patch:
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Systems running a RELEASE version of FreeBSD on the i386 or amd64
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platforms can be updated via the freebsd-update(8) utility:
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# freebsd-update fetch
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# freebsd-update install
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# shutdown -r +10min "Rebooting for an errata update"
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2) To update your system via a source code patch:
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The following patches have been verified to apply to the applicable
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FreeBSD release branches.
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a) Download the relevant patch from the location below, and verify the
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detached PGP signature using your PGP utility.
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# fetch https://security.FreeBSD.org/patches/EN-20:02/nmount.patch
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# fetch https://security.FreeBSD.org/patches/EN-20:02/nmount.patch.asc
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# gpg --verify nmount.patch.asc
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b) Apply the patch. Execute the following commands as root:
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# cd /usr/src
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# patch < /path/to/patch
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c) Recompile your kernel as described in
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<URL:https://www.FreeBSD.org/handbook/kernelconfig.html> and reboot the
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system.
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VI. Correction details
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The following list contains the correction revision numbers for each
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affected branch.
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Branch/path Revision
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- -------------------------------------------------------------------------
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stable/12/ r353032
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releng/12.1/ r353104
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releng/12.0/ r357216
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stable/11/ r353109
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releng/11.3/ r357216
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- -------------------------------------------------------------------------
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To see which files were modified by a particular revision, run the
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following command, replacing NNNNNN with the revision number, on a
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machine with Subversion installed:
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# svn diff -cNNNNNN --summarize svn://svn.freebsd.org/base
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Or visit the following URL, replacing NNNNNN with the revision number:
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<URL:https://svnweb.freebsd.org/base?view=revision&revision=NNNNNN>
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VII. References
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The latest revision of this advisory is available at
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<URL:https://security.FreeBSD.org/advisories/FreeBSD-EN-20:02.nmount.asc>
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