FreeBSD Security Advisories
2019-Aug-20 20:13 UTC
[FreeBSD-Announce] FreeBSD Security Advisory FreeBSD-SA-19:24.mqueuefs
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA512
============================================================================FreeBSD-SA-19:24.mqueuefs
Security Advisory
The FreeBSD Project
Topic: Reference count overflow in mqueue filesystem 32-bit compat
Category: core
Module: kernel
Announced: 2019-08-20
Credits: Karsten K??nig, Secfault Security
Affects: All supported versions of FreeBSD.
Corrected: 2019-08-20 17:45:22 UTC (stable/12, 12.0-STABLE)
2019-08-20 17:51:32 UTC (releng/12.0, 12.0-RELEASE-p10)
2019-08-20 17:46:22 UTC (stable/11, 11.3-STABLE)
2019-08-20 17:51:32 UTC (releng/11.3, 11.3-RELEASE-p3)
2019-08-20 17:51:32 UTC (releng/11.2, 11.2-RELEASE-p14)
CVE Name: CVE-2019-5603
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/>.
Note: This issue is related to the previously disclosed SA-19:15.mqueuefs.
It is another instance of the same bug and as such shares the same CVE.
I. Background
mqueuefs(5) implements POSIX message queue file system which can be used
by processes as a communication mechanism.
'struct file' represents open files, directories, sockets and other
entities.
II. Problem Description
System calls operating on file descriptors obtain a reference to
relevant struct file which due to a programming error was not always put
back, which in turn could be used to overflow the counter of affected
struct file.
III. Impact
A local user can use this flaw to obtain access to files, directories,
sockets, etc., opened by processes owned by other users. If obtained
struct file represents a directory from outside of user's jail, it can
be used to access files outside of the jail. If the user in question is
a jailed root they can obtain root privileges on the host system.
IV. Workaround
No workaround is available. Note that the mqueuefs file system is not
enabled by default.
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 "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-19:24/mqueuefs.patch
# fetch https://security.FreeBSD.org/patches/SA-19:24/mqueuefs.patch.asc
# gpg --verify mqueuefs.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/ r351255
releng/12.0/ r351261
stable/11/ r351257
releng/11.3/ r351261
releng/11.2/ r351261
- -------------------------------------------------------------------------
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
<other info on vulnerability>
<URL:https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-5603>
The latest revision of this advisory is available at
<URL:https://security.FreeBSD.org/advisories/FreeBSD-SA-19:24.mqueuefs.asc>
-----BEGIN PGP SIGNATURE-----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1dwe
-----END PGP SIGNATURE-----