-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA512

=============================================================================
FreeBSD-SA-19:17.fd                                         Security Advisory
                                                          The FreeBSD Project

Topic:          File description reference count leak

Category:       core
Module:         unix
Announced:      2019-07-24
Credits:        Mark Johnston
Affects:        All supported versions of FreeBSD.
Corrected:      2019-07-22 19:25:05 UTC (stable/12, 12.0-STABLE)
                2019-07-24 12:57:49 UTC (releng/12.0, 12.0-RELEASE-p8)
                2019-07-22 19:27:23 UTC (stable/11, 11.2-STABLE)
                2019-07-24 12:57:49 UTC (releng/11.2, 11.2-RELEASE-p12)
                2019-07-24 12:57:49 UTC (releng/11.3, 11.3-RELEASE-p1)
CVE Name:       CVE-2019-5607

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

UNIX-domain sockets are used for inter-process communication.  It is
possible to use UNIX-domain sockets to transfer rights, encoded as file
descriptors, to another process.  Rights are encapsulated in control
messages, and multiple such messages may be transmitted with a single
system call.

II.  Problem Description

If a process attempts to transmit rights over a UNIX-domain socket and
an error causes the attempt to fail, references acquired on the rights
are not released and are leaked.  This bug can be used to cause the
reference counter to wrap around and free the corresponding file
structure.

III. Impact

A local user can exploit the bug to gain root privileges or escape from
a jail.

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.

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.

[FreeBSD 11.2]
# fetch https://security.FreeBSD.org/patches/SA-19:17/fd.11.2.patch
# fetch https://security.FreeBSD.org/patches/SA-19:17/fd.11.2.patch.asc
# gpg --verify fd.11.2.patch.asc

[FreeBSD 11.3]
# fetch https://security.FreeBSD.org/patches/SA-19:17/fd.11.patch
# fetch https://security.FreeBSD.org/patches/SA-19:17/fd.11.patch.asc
# gpg --verify fd.11.patch.asc

[FreeBSD 12.0]
# fetch https://security.FreeBSD.org/patches/SA-19:17/fd.12.patch
# fetch https://security.FreeBSD.org/patches/SA-19:17/fd.12.patch.asc
# gpg --verify fd.12.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/                                                        r350222
releng/12.0/                                                      r350286
stable/11/                                                        r350223
releng/11.2/                                                      r350286
releng/11.3/                                                      r350286
- -------------------------------------------------------------------------

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-2019-5607>

The latest revision of this advisory is available at
<URL:https://security.FreeBSD.org/advisories/FreeBSD-SA-19:17.fd.asc>
-----BEGIN PGP SIGNATURE-----
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=juJj
-----END PGP SIGNATURE-----