FreeBSD Security Advisory FreeBSD-SA-16:04.linux

Fabricante: FreeBSD
Fecha: 14/01/2016
Identificador: FreeBSD-SA-16:04.linux
FreeBSD Security Advisory FreeBSD-SA-16:04.linux
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 ============================================================================= FreeBSD-SA-16:04.linux Security Advisory The FreeBSD Project Topic: Linux compatibility layer setgroups(2) system call vulnerability Category: core Module: kernel Announced: 2016-01-14 Credits: Dmitry Chagin Affects: All supported versions of FreeBSD Corrected: 2016-01-14 09:11:42 UTC (stable/10, 10.2-STABLE) 2016-01-14 09:10:46 UTC (releng/10.2, 10.2-RELEASE-p9) 2016-01-14 09:11:16 UTC (releng/10.1, 10.1-RELEASE-p26) 2016-01-14 09:11:48 UTC (stable/9, 9.3-STABLE) 2016-01-14 09:11:26 UTC (releng/9.3, 9.3-RELEASE-p33) CVE Name: CVE-2016-1881 For general information regarding FreeBSD Security Advisories, including descriptions of the fields above, security branches, and the following sections, please visit . I. Background FreeBSD is binary-compatible with the Linux operating system through a loadable kernel module/optional kernel component. The support is provided on amd64 and i386 machines. II. Problem Description A programming error in the Linux compatibility layer setgroups(2) system call can lead to an unexpected results, such as overwriting random kernel memory contents. III. Impact It is possible for a local attacker to overwrite portions of kernel memory, which may result in a privilege escalation or cause a system panic. IV. Workaround No workaround is available, but systems not using the Linux binary compatibility layer are not vulnerable. The following command can be used to test if the Linux binary compatibility layer is loaded: # kldstat -m linuxelf V. Solution Perform one of the following: 1) Upgrade your vulnerable system to a supported FreeBSD stable or release / security branch (releng) dated after the correction date. Reboot the system or unload and reload the linux.ko kernel module. 2) 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 Reboot the system or unload and reload the linux.ko kernel module. 3) 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-16:04/linux.patch # fetch https://security.FreeBSD.org/patches/SA-16:04/linux.patch.asc # gpg --verify linux.patch.asc b) Apply the patch. Execute the following commands as root: # cd /usr/src # patch < /path/to/patch # cd /usr/src/amd64/linux32 # make sysent # cd /usr/src/i386/linux # make sysent c) Recompile your kernel as described in . Reboot the system or unload and reload the linux.ko kernel module. VI. Correction details The following list contains the correction revision numbers for each affected branch. Branch/path Revision - ------------------------------------------------------------------------- stable/9/ r293898 releng/9.3/ r293896 stable/10/ r293897 releng/10.1/ r293894 releng/10.2/ r293893 - ------------------------------------------------------------------------- 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: VII. References The latest revision of this advisory is available at -----BEGIN PGP SIGNATURE----- iQIcBAEBCgAGBQJWl2j3AAoJEO1n7NZdz2rnstMP/jddSJehSXe9rlL2qhYfRrQY XZSuoOtolvcl2xSQCZYprXN95/i890VOdJ9x4+iYJA2IQO55a8MjS1DcJjjonV7J zJa7Apnu1jaK1jDx+RL6C3eVDff0ss1B7NvZTXmjHn+nIsIRxd6vzxDp2NujTnWS XHNinNAPcVK9Hy/AJh1W+mClvgLg+lyMICuraMjTDc5ML3+fxUmXfDUWq1mm2Chq uYXMXcIBXBJx1mnnm9n2izExr7j7AHaVJywe/UYk+KCNbSeags76pt1vuPfoOjdE BaSlX9KNMouYU0JNfv/wC7/UnuQ/BY1XzxheVpIqmXwlFstAmSiKYIQkpIuypVF1 yUmf8CjN6AOx9P5CjxX88eeY3F6J1yohch1AI4IMqT3F3fd5LbJ5WqOjritt0J96 hDjnsiVhw4ozQE6SWTY8TKlokOOEfJC+yhNIJ0cNaHnkLSCUuDDErtGzp1CYoYmt Q8D1VJ1UEaVPaKcaNAo4+sjiE1uK6svPiWa1+W9VbKGvc3Y7PbcuVIzU0aI4ySgj VecEFM1O5wr3WXIYnDQNwkWVxbCQdxOIPyW0rqMGQVpu1h7MKk0oMboY1bLcQYFy Aa9okOl+D7ItpEpRUgnIT06B6krC5sUQuzkUxnVIBPKtcl1OZ4B8KidLjEqu4BSx 3qOQSGqZzr8TFcwPIJv4 =JKVW -----END PGP SIGNATURE-----