FreeBSD Security Advisory FreeBSD-SA-18:07.lazyfpu
21 June, 2018 by firstname.lastname@example.org | freebsd
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 ============================================================================= FreeBSD-SA-18:07.lazyfpu Security Advisory The FreeBSD Project Topic: Lazy FPU State Restore Information Disclosure Category: core Module: kernel Announced: 2018-06-21 Credits: Julian Stecklina from Amazon Germany Thomas Prescher from Cyberus Technology GmbH Zdenek Sojka from SYSGO AG Colin Percival Affects: All supported version of FreeBSD. Corrected: 2018-06-14 18:50:49 UTC (stable/11, 11.2-PRERELEASE) 2018-06-15 13:21:37 UTC (releng/11.2, 11.2-RC3) 2018-06-21 05:17:13 UTC (releng/11.1, 11.1-RELEASE-p11) CVE Name: CVE-2018-3665 Special Note: This advisory only addresses this issue for FreeBSD 11.x on i386 and amd64. We expect to update this advisory to include 10.x in the near future. For general information regarding FreeBSD Security Advisories, including descriptions of the fields above, security branches, and the following sections, please visit <URL:https://security.FreeBSD.org/>. I. Background Modern CPUs have a floating point unit (FPU) which needs to maintain state per thread. One technique is to only save and to only restore the FPU state for a thread when a thread attempts to utilize the FPU. This technique is called Lazy FPU state restore. II. Problem Description A subset of Intel processors can allow a local thread to infer data from another thread through a speculative execution side channel when Lazy FPU state restore is used. III. Impact Any local thread can potentially read FPU state information from other threads running on the host. This could include cryptographic keys when the AES-NI CPU feature is present. IV. Workaround No workaround is available, but non-Intel branded CPUs are not believed to be vulnerable. V. Solution The patch changes from Lazy FPU state restore to Eager FPU state restore. This new technique is the recommended practice from Intel and in some cases can actually increase performance, depending on workload. 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. Afterward, reboot the system. 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 Afterward, reboot the system. 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. [FreeBSD 11.1] # fetch https://security.FreeBSD.org/patches/SA-18:07/lazyfpu-11.patch # fetch https://security.FreeBSD.org/patches/SA-18:07/lazyfpu-11.patch.asc # gpg --verify lazyfpu-11.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/11/ r335169 releng/11.2/ r335196 releng/11.1/ r335465 - ------------------------------------------------------------------------- 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://www.intel.com/content/www/us/en/security-center/advisory/intel-sa-00145.html> <URL:https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-3665> The latest revision of this advisory is available at <URL:https://security.FreeBSD.org/advisories/FreeBSD-SA-18:07.lazyfpu.asc> -----BEGIN PGP SIGNATURE----- iQKTBAEBCgB9FiEE/A6HiuWv54gCjWNV05eS9J6n5cIFAlsrN1hfFIAAAAAALgAo aXNzdWVyLWZwckBub3RhdGlvbnMub3BlbnBncC5maWZ0aGhvcnNlbWFuLm5ldEZD MEU4NzhBRTVBRkU3ODgwMjhENjM1NUQzOTc5MkY0OUVBN0U1QzIACgkQ05eS9J6n 5cJTLA/+Kt7QLkNCVudaiE+d+VMuC2f1aGhqoyd+36xL9rNsn2ShZhIo+gq1dhXn 2lJiOYCPN5cJkasj1YdP2bSIv25nTcFMp0rKOww0A1scOnzi66LAD+DXmGVUhmaA MPyrnuL7rbuPq9ls9FGAO2XURwB9IrGYtqPuVWmNyn+HyKBYcGCkL5+UEnHeUCg8 oopJudZgrGBVMFCsqG6K/b+3uc397Hyq0PZzpyWFfkaxrbTwVMMwgWyTxIYaPVs7 2g7WK2JWjJNk0IWQGot9qpKYDRyxc9PPFX/0blwOLe1Wwrt5nEF+9av89HQJ6PXF +Ws5w8Gnhi9wWuK19ew1j0nvP+f0zw09r4GuEzhZXADAz733HNK5dtsS/dMJi2wa 9fQ0s1joT3JFDvWZKUQS2mNuhpvBfYoI0d0OEJT2H2eycFYe4B+VNhB2V1e9wLn6 9X4+Vbc2LEOF09klQQFMYNMEyQzLtfq2gHIoD37sCw9mMrYKWjgy3NhY5AKrfGHG OcBsvnaXCW/x9/kV9Pfoel/psrmjcQdp4QEKAZbRNwvJG5sGhtsQXTp0Nk+BCuVy G0NNB9306dLfk0OTZ02SiOUjVagXObyo+LgWTBO6FryDlHVkopsYNkB5oRx9fLrm 68r7OXidl0ndGqnh87meMVH1/Fu/rr09Jd4osIzS+Gc0Dt7NOEQ= =8fnI -----END PGP SIGNATURE----- _______________________________________________ email@example.com mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-announce To unsubscribe, send any mail to "firstname.lastname@example.org"