FreeBSD Security Advisory FreeBSD-SA-16:15.sysarch

Fabricante: FreeBSD
Fecha: 17/03/2016
Identificador: FreeBSD-SA-16:15.sysarch
FreeBSD Security Advisory FreeBSD-SA-16:15.sysarch
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 ============================================================================= FreeBSD-SA-16:15.sysarch Security Advisory The FreeBSD Project Topic: Incorrect argument validation in sysarch(2) Category: core Module: kernel Announced: 2016-03-16 Credits: Core Security Affects: All supported versions of FreeBSD. Corrected: 2016-03-16 22:35:55 UTC (stable/10, 10.2-STABLE) 2016-03-16 22:31:04 UTC (releng/10.2, 10.2-RELEASE-p14) 2016-03-16 22:30:56 UTC (releng/10.1, 10.1-RELEASE-p31) 2016-03-16 22:36:02 UTC (stable/9, 9.3-STABLE) 2016-03-16 22:30:03 UTC (releng/9.3, 9.3-RELEASE-p39) CVE Name: CVE-2016-1885 For general information regarding FreeBSD Security Advisories, including descriptions of the fields above, security branches, and the following sections, please visit . I. Background The IA-32 architecture allows programs to define segments, which provides based and size-limited view into the program address space. The memory-resident processor structure, called Local Descriptor Table, usually abbreviated LDT, contains definitions of the segments. Since incorrect or malicious segments would breach system integrity, operating systems do not provide processes direct access to the LDT, instead they provide system calls which allow controlled installation and removal of segments. II. Problem Description A special combination of sysarch(2) arguments, specify a request to uninstall a set of descriptors from the LDT. The start descriptor is cleared and the number of descriptors are provided. Due to invalid use of a signed intermediate value in the bounds checking during argument validity verification, unbound zero'ing of the process LDT and adjacent memory can be initiated from usermode. III. Impact This vulnerability could cause the kernel to panic. In addition it is possible to perform a local Denial of Service against the system by unprivileged processes. IV. Workaround No workaround is available, but only the amd64 architecture is affected. 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 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-16:15/sysarch.patch # fetch https://security.FreeBSD.org/patches/SA-16:15/sysarch.patch.asc # gpg --verify sysarch.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/ r296958 releng/9.3/ r296953 stable/10/ r296957 releng/10.1/ r296954 releng/10.2/ r296955 - ------------------------------------------------------------------------- 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----- iQIcBAEBCgAGBQJW6eO/AAoJEO1n7NZdz2rn0UMP/iU/orN0P6+Rsj9hY2B6M0VS H6CMMVvketkIIWl9oKX9D/G0g/HyD8uFy06qL2OBz+h99h1oaF5ELl4G6TkF69Ra yOKrLcWnyi3eWLUaPvGkrLakVpG0+pU3QRvBT+d0nsTarOMPq+nhooarMfAluF3p c3bXEjzn/lTA5T0zTcGS2o9IgORvYrKRIGW0KJDsCWsDgVyWngsJAJdIrzwx022Q ENoIGmgLnYsx7TY1cuMtdb3TVyJsZv8zjrrmcLzw67Vly7wShs22CKK23ydDDyy9 xFYsbWA+X8CarV2uSk8xJCIbWjJSlfc9XvOlHLZEiT7PNCZIk2c2fNLENxHvyNl1 vgIUBoD/wzzS5QqdnT4r726aQt3pNezns1NDxujwUovVn5nQaXnKOTJHsOthDJ99 PakEMa93iZqOfzbVouBIBH1IPgNLHof9Jdq3wYiKhrQVJXRespdpCfh3/wdph9LB ElBOTlrCcShV+N6deO4KI2wNK5h704D4hOMsqlInLwGQmGi7qa4ouWASgzQQmU/8 6va3mJsgCvzHUpRCMQo7pIZm6SnOIYLdg7S4vV7P6q5oOIBnjFa8bK/Cq+zOR42e gJs9ou65JTTC0KG+26wXaD2Wx8uriO/+ZfCT/YM29FUUqIdayqHxhACjF0lkY83P 02CAQXURVoI7kbjHaGT7 =jV9z -----END PGP SIGNATURE-----