Date: Thu, 27 Sep 2018 20:08:54 +0000 (UTC) From: FreeBSD Errata Notices <errata-notices@freebsd.org> To: FreeBSD Errata Notices <errata-notices@freebsd.org> Subject: [FreeBSD-Announce] FreeBSD Errata Notice FreeBSD-EN-18:11.listen Message-ID: <20180927200854.35DAD14B77@freefall.freebsd.org>
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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 ============================================================================= FreeBSD-EN-18:11.listen Errata Notice The FreeBSD Project Topic: Denial of service in listen syscall over IPv6 socket Category: core Module: kernel Announced: 2018-09-27 Credits: Jakub Jirasek, Secunia Research at Flexera Affects: All supported versions of FreeBSD. Corrected: 2018-09-27 18:50:10 UTC (stable/11, 11.2-STABLE) 2018-09-27 18:34:42 UTC (releng/11.2, 11.2-RELEASE-p4) 2018-09-27 18:34:42 UTC (releng/11.1, 11.1-RELEASE-p15) 2018-09-27 18:48:50 UTC (stable/10, 10.4-STABLE) 2018-09-27 18:34:42 UTC (releng/10.4, 10.4-RELEASE-p13) CVE Name: CVE-2018-6925 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 The protocol control block is a structure that maintains the network layer state for various sockets. There are various state flags that must be properly maintained to keep the structure consistent. II. Problem Description There are various cases in the IPv6 socket code where the protocol control block's state flags are modified during a syscall, but are not restored if the operation fails. This can leave the control block in an inconsistent state. III. Impact A local unprivileged user could exploit the inconsistent state of the protocol control block to cause the kernel to crash, leading to a denial of service. IV. Workaround No workaround is available. 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. Afterward, 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 Afterward, 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.x] # fetch https://security.FreeBSD.org/patches/EN-18:11/listen-11.patch # fetch https://security.FreeBSD.org/patches/EN-18:11/listen-11.patch.asc # gpg --verify listen-11.patch.asc [FreeBSD 10.4] # fetch https://security.FreeBSD.org/patches/EN-18:11/listen-10.patch # fetch https://security.FreeBSD.org/patches/EN-18:11/listen-10.patch.asc # gpg --verify listen-10.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/10/ r338985 releng/10.4/ r338980 stable/11/ r338986 releng/11.1/ r338980 releng/11.2/ r338980 - ------------------------------------------------------------------------- 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-2018-6925> For information about Secunia Research: <URL:https://www.flexerasoftware.com/enterprise/company/about/secunia-research/> The latest revision of this advisory is available at <URL:https://security.FreeBSD.org/advisories/FreeBSD-EN-18:11.listen.asc> -----BEGIN PGP SIGNATURE----- iQKTBAEBCgB9FiEE/A6HiuWv54gCjWNV05eS9J6n5cIFAlutKURfFIAAAAAALgAo aXNzdWVyLWZwckBub3RhdGlvbnMub3BlbnBncC5maWZ0aGhvcnNlbWFuLm5ldEZD MEU4NzhBRTVBRkU3ODgwMjhENjM1NUQzOTc5MkY0OUVBN0U1QzIACgkQ05eS9J6n 5cIUEA/+JxBo76dRre8nfvYcN2PJGGFn8i2mWwSG87SWwQUeKlkgpJCV8qMnVEr2 dGz3gwBsxFLKUjQVyl+IwFkaJgKXMbFYkfIqLaS+3a12KLllFAn2Q0dnN+oxFhS2 Wpx4DkDRgBzEyLokxwjUCtg2fd6HPlML2YXCR5SqjXDOoBGAR9GCCXXYNnWSC00y IYgeC8UpE3ykTlwDH8q+LgLqtnx/oDW1h6UR12alP0ytH8+BldiAqRxjHE3/Wv2E aU8m8YuAAIW4tHZ4vdqpiFP4grN/0tSf/DEPBTtVIv5FGpXSk61YTBSm4OMIKNN8 QEVEA6n6NEGSKYrbB5BE73KYgCAaeGzcGikX9F4aAlN5GSPBVJ66SEbk16YDzDfB KimjhityEP5YXh8hVkNo6fq+17dKpqx81390wzcXeDlBTIkANnKLh23gE0RuniNY dXrPE2HWSpkCnWN6l0BImefDeCgAaF7KZK+z7bbsn2D7UMGFGeHU/XlRM0ze7OOV ETqwk2M4GuxddHTKktNGBItWVd6EjReAh6QOo1kAA4qMKuNIiDQdRS72x6fUbmlA ZIOzPNd6TS57aKSnAZlR1SpvRMqo+g9cetMxuJmKnQ+hXaRk2zJVuP2RAJuoFFqf TmnVAPpDRjoYa0lf2YkOKtYcfF+pBcWI1CVAEFuQG2PheJRYns0= =jMY6 -----END PGP SIGNATURE-----
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