FreeBSD Errata Notices
2014-Jun-24 19:33 UTC
[FreeBSD-Announce] FreeBSD Errata Notice FreeBSD-EN-14:07.pmap
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 ============================================================================FreeBSD-EN-14:07.pmap Errata Notice The FreeBSD Project Topic: Bug with PCID implementation Category: core Module: kernel Announced: 2014-06-24 Credits: Henrik Gulbrandsen Affects: FreeBSD 10.0-RELEASE Corrected: 2014-03-04 21:51:09 UTC (stable/10, 10.0-STABLE) 2014-06-24 19:05:08 UTC (releng/10.0, 10.0-RELEASE-p6) 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:http://security.freebsd.org/>. I. Background Process-context identifiers (PCIDs) are a facility in modern x86 processors, which tags TLB entries with the Id of the address space and allows to avoid TLB invalidation on the context switch. II. Problem Description Due to bug in the handling of the mask of the CPU set where the given address space could have cached TLB entries, stale mappings could be seen by multithreaded programs. III. Impact Applications, most notably Java, which makes heavy use of threads may randomly crash due to the inconcistency. IV. Workaround Systems that do not run have a CPU that supports the Process-Context Identifiers feature are not affected. The system administrator can add the following to /boot/loader.conf which disables Process-Context Identifiers to workaround this problem: vm.pmap.pcid_enabled="0" 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. 2) To update your present 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 10.0] # fetch http://security.FreeBSD.org/patches/EN-14:07/pmap.patch # fetch http://security.FreeBSD.org/patches/EN-14:07/pmap.patch.asc # gpg --verify pmap.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:http://www.FreeBSD.org/handbook/kernelconfig.html> and reboot the system. 3) 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 VI. Correction details The following list contains the revision numbers of each file that was corrected in FreeBSD. Branch/path Revision - ------------------------------------------------------------------------- stable/10/ r262753 releng/10.0/ r267829 - ------------------------------------------------------------------------- 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:http://svnweb.freebsd.org/base?view=revision&revision=NNNNNN> VII. References The latest revision of this Errata Notice is available at http://security.FreeBSD.org/advisories/FreeBSD-EN-14:07.pmap.asc -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIcBAEBCgAGBQJTqc+KAAoJEO1n7NZdz2rnAbYP/iZKU3SSwHwWPzYa03ZwgW4u 54MigJuV/wyOfJj2ZZuOXTaYZP1miRgFr7mn9OWkA6slWHLAVkmN9fWrUU8tRPjJ UDVhnbToVYIcmW2tEH5lZ5y1Stt178NZTeMo26jgkWhj74RZ10OIFdSuNlNUQGSr djanCdgpnGL+odml+rQcGAAKKH97PchQ6r9IivNgE6mnGhGvzOjQOSdxioBLew14 w5Ua3k4nn/4hYi4RMPJ/vAlPdJHVsnZb8kRWhf4Ncj19IkvJ8EO6PmnHCbdGmV1I cvqVFxXPGGA/A+O9E+1S+54SWotivpgjSujuQFFmvuzBbPhlt/Hmtn6YwljNG4+e V6MsMRPMHVoIhOCBv9xfCHgyajA7jgbRGqQkMWxwKPVLjmk2NWOsbGBjHMFHnqYn 87Sh7crbFffNGwqGJgn+vXSXeNZ/95EWSBE0/B4KfqPeX6XCJI/C/sMRl0ATKa7C k227J0olXKKUInLEq7tS1nLS0IKlWLF5WiRFx7DOa4DKLBcLZkYKTu3ATJySQ4V3 hDNDpubB3/94ug1slRNWDYGxzaZq0ctUTubxsHW7a0iYQi/PkssCT/8jVAdsx8hq S1DjGZiFAKLOiJUSvPfONdwodORyEyMB+z37EfgeHKKqnjJXgSEtmnmI+7sT8hlR FhXX1XQOBUtPxF+MY4bT =vNzu -----END PGP SIGNATURE-----