FreeBSD Security Advisory FreeBSD-SA-16:20.linux

Fabricante: FreeBSD
Fecha: 31/05/2016
Identificador: FreeBSD-SA-16:20.linux
FreeBSD Security Advisory FreeBSD-SA-16:20.linux
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 ============================================================================= FreeBSD-SA-16:20.linux Security Advisory The FreeBSD Project Topic: Kernel stack disclosure in Linux compatibility layer Category: core Module: linux(4) Announced: 2016-05-31 Credits: CTurt Affects: All supported versions of FreeBSD. Corrected: 2016-05-31 16:57:42 UTC (stable/10, 10.3-STABLE) 2016-05-31 16:55:50 UTC (releng/10.3, 10.3-RELEASE-p4) 2016-05-31 16:55:45 UTC (releng/10.2, 10.2-RELEASE-p18) 2016-05-31 16:55:41 UTC (releng/10.1, 10.1-RELEASE-p35) 2016-05-31 16:58:00 UTC (stable/9, 9.3-STABLE) 2016-05-31 16:55:37 UTC (releng/9.3, 9.3-RELEASE-p43) 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 for amd64 and i386 machines. II. Problem Description The implementation of the TIOCGSERIAL ioctl(2) does not clear the output struct before copying it out to userland. The implementation of the Linux sysinfo() system call does not clear the output struct before copying it out to userland. III. Impact An unprivileged user can read a portion of uninitialised kernel stack data, which may contain sensitive information, such as the stack guard, portions of the file cache or terminal buffers, which an attacker might leverage to obtain elevated privileges. IV. Workaround No workaround is available, but systems not using the Linux binary compatibility layer are not vulnerable. The Linux compatibility layer is not included in the default GENERIC kernel. 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 is required. 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 is required. 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-16:20/linux.patch # fetch https://security.FreeBSD.org/patches/SA-16:20/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 c) Recompile your kernel as described in and reboot the system. VI. Correction details The following list contains the correction revision numbers for each affected branch. Branch/path Revision - ------------------------------------------------------------------------- stable/9/ r301055 releng/9.3/ r301049 stable/10/ r301054 releng/10.1/ r301050 releng/10.2/ r301051 releng/10.3/ r301052 - ------------------------------------------------------------------------- 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----- iQIcBAEBCgAGBQJXTcSOAAoJEO1n7NZdz2rnjSMP/AsGK5jda/QlrRrpvKyd3HGr qVsTzro+a2ed2ZlUCamM/JICXfbAit+dOioui+CIN1IKai/mxNPMpIWcPRx1AhDr 3y52MmSzkCqK6QT3tvwYYaG4uOZ3/wbWAJ8EKz2qqYlZ4hkmy24BdvTCGB2SGDgo Nz1P60NWxaqafCwFyb0xz7Lful52txSLIr9mWZzTcSgwNNEscGiMgzXiY64GlWfQ r20udpFrPG5+OOwpFAdR4IImQA7B0AYD064NbzN9A+mJlbhtGguDS3oTkbVBVIbF ldLgDkrFeIv/Jyhvij1q85xfuOxT6eaVJe7qGUaV8v6qQx17VhH8j0sVzn6nh0w9 kly4FB0osyZRQJ7bV7c+FVGECUWRyzSpeo7lx6ICXECuyzcX9U4IxC0oxPcokD3o CEOJkQEjLtMSfKdE143lbyPCtZUMSXtp/CLEUxW7eDCbW89O7p7pv6xTiNLdopVT cpUcF+Y0KepwMrg+jXH8i07yF6QgqRWVziA16821OJ4ThD0RN4MRrWUizl/1J2iD LFGxK8l2U3hP5dhXpYpEHsI2xkU94Lojp0SfngFoylo4Z8UjpQeaR9NG+F3+uR45 Q8aGB3CQe84JZUzFfVN6292AE/4ZMg13iRzKUawV8JBUEWG+MnrtU6a7zwIRVM2F zT2f1EP7488fCSxbmicf =bohu -----END PGP SIGNATURE-----