146 lines
5.5 KiB
Text
146 lines
5.5 KiB
Text
-----BEGIN PGP SIGNED MESSAGE-----
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Hash: SHA512
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=============================================================================
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FreeBSD-SA-19:17.fd Security Advisory
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The FreeBSD Project
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Topic: File description reference count leak
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Category: core
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Module: unix
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Announced: 2019-07-24
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Credits: Mark Johnston
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Affects: All supported versions of FreeBSD.
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Corrected: 2019-07-22 19:25:05 UTC (stable/12, 12.0-STABLE)
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2019-07-24 12:57:49 UTC (releng/12.0, 12.0-RELEASE-p8)
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2019-07-22 19:27:23 UTC (stable/11, 11.2-STABLE)
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2019-07-24 12:57:49 UTC (releng/11.2, 11.2-RELEASE-p12)
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2019-07-24 12:57:49 UTC (releng/11.3, 11.3-RELEASE-p1)
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CVE Name: CVE-2019-5607
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For general information regarding FreeBSD Security Advisories,
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including descriptions of the fields above, security branches, and the
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following sections, please visit <URL:https://security.FreeBSD.org/>.
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I. Background
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UNIX-domain sockets are used for inter-process communication. It is
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possible to use UNIX-domain sockets to transfer rights, encoded as file
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descriptors, to another process. Rights are encapsulated in control
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messages, and multiple such messages may be transmitted with a single
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system call.
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II. Problem Description
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If a process attempts to transmit rights over a UNIX-domain socket and
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an error causes the attempt to fail, references acquired on the rights
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are not released and are leaked. This bug can be used to cause the
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reference counter to wrap around and free the corresponding file
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structure.
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III. Impact
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A local user can exploit the bug to gain root privileges or escape from
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a jail.
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IV. Workaround
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No workaround is available.
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V. Solution
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Upgrade your vulnerable system to a supported FreeBSD stable or
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release / security branch (releng) dated after the correction date.
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Perform one of the following:
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1) To update your vulnerable 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 a security update"
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2) To update your vulnerable 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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[FreeBSD 11.2]
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# fetch https://security.FreeBSD.org/patches/SA-19:17/fd.11.2.patch
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# fetch https://security.FreeBSD.org/patches/SA-19:17/fd.11.2.patch.asc
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# gpg --verify fd.11.2.patch.asc
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[FreeBSD 11.3]
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# fetch https://security.FreeBSD.org/patches/SA-19:17/fd.11.patch
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# fetch https://security.FreeBSD.org/patches/SA-19:17/fd.11.patch.asc
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# gpg --verify fd.11.patch.asc
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[FreeBSD 12.0]
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# fetch https://security.FreeBSD.org/patches/SA-19:17/fd.12.patch
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# fetch https://security.FreeBSD.org/patches/SA-19:17/fd.12.patch.asc
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# gpg --verify fd.12.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/ r350222
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releng/12.0/ r350286
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stable/11/ r350223
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releng/11.2/ r350286
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releng/11.3/ r350286
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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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<URL:https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-5607>
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The latest revision of this advisory is available at
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<URL:https://security.FreeBSD.org/advisories/FreeBSD-SA-19:17.fd.asc>
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