FreeBSD Errata Notices
2018-Nov-27 21:22 UTC
[FreeBSD-Announce] FreeBSD Errata Notice FreeBSD-EN-18:13.icmp
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA512
============================================================================FreeBSD-EN-18:13.icmp
Errata Notice
The FreeBSD Project
Topic: ICMP buffer underwrite
Category: core
Module: kernel
Announced: 2018-11-27
Affects: All supported versions of FreeBSD.
Corrected: 2018-11-08 21:58:51 UTC (stable/11, 11.2-STABLE)
2018-11-27 19:43:16 UTC (releng/11.2, 11.2-RELEASE-p5)
CVE Name: CVE-2018-17156
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
ICMP messages are control messages used to send error messages and
operational information.
II. Problem Description
The icmp_error routine allocates either an mbuf or a cluster depending on the
size of the data to be quoted in the ICMP reply, but the calculation failed
to account for additional padding on 64-bit platforms when using a
non-default sysctl value for net.inet.icmp.quotelen.
III. Impact
For systems that set net.inet.icmp.quotelen to a non-default value, a buffer
underwrite condition occurs.
IV. Workaround
Reset net.inet.icmp.quotelen to default value of 8 using sysctl(8):
# sysctl net.inet.icmp.quotelen=8
V. Solution
Perform one of the following:
1) Upgrade your system to a supported FreeBSD stable or release / security
branch (releng) dated after the correction date.
Afterwards, reboot the system.
2) 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
Afterwards, reboot the system.
3) 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.
[FreeBSD 11.2]
# fetch https://security.FreeBSD.org/patches/EN-18:13/icmp.patch
# fetch https://security.FreeBSD.org/patches/EN-18:13/icmp.patch.asc
# gpg --verify icmp.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/11/ r340268
releng/11.2/ r341089
- -------------------------------------------------------------------------
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 the problem>
<URL:https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-17156>
<URL:https://www.reddit.com/r/BSD/comments/9v6xwg/remotely_triggerable_icmp_buffer_underwrite_in/>
The latest revision of this advisory is available at
<URL:https://security.FreeBSD.org/advisories/FreeBSD-EN-18:13.icmp.asc>
-----BEGIN PGP SIGNATURE-----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kqz6
-----END PGP SIGNATURE-----