FreeBSD Security Advisories
2017-Nov-21 04:02 UTC
FreeBSD Security Advisory FreeBSD-SA-17:10.kldstat [REVISED]
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 ============================================================================FreeBSD-SA-17:10.kldstat Security Advisory The FreeBSD Project Topic: Information leak in kldstat(2) Category: core Module: kernel Announced: 2017-11-15 Credits: Ilja van Sprundel TJ Corley Affects: All supported versions of FreeBSD. Corrected: 2017-11-15 22:34:15 UTC (stable/11, 11.1-STABLE) 2017-11-15 22:49:47 UTC (releng/11.1, 11.1-RELEASE-p4) 2017-11-15 22:50:20 UTC (releng/11.0, 11.0-RELEASE-p15) 2017-11-15 22:35:16 UTC (stable/10, 10.4-STABLE) 2017-11-15 22:50:47 UTC (releng/10.4, 10.4-RELEASE-p3) 2017-11-15 22:51:08 UTC (releng/10.3, 10.3-RELEASE-p24) CVE Name: CVE-2017-1088 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/>. 0. Revision history v1.0 2017-11-15 Initial release. v1.1 2017-11-20 Corrected credit. Ilja van Sprundel first reported the issue to the project, but wasn't cited. The FreeBSD Security Team apologizes to Ilja for this oversight. I. Background The kldstat(2) syscall provides information about loaded kld files. The syscall takes a userland argument of struct kld_file_stat which is then filled with data about the kld file requested. II. Problem Description The kernel does not properly clear the memory of the kld_file_stat structure before filling the data. Since the structure filled by the kernel is allocated on the kernel stack and copied to userspace, a leak of information from the kernel stack is possible. III. Impact Some bytes from the kernel stack can be observed in userspace. IV. Workaround No workaround is available. 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. 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. # fetch https://security.FreeBSD.org/patches/SA-17:10/kldstat.patch # fetch https://security.FreeBSD.org/patches/SA-17:10/kldstat.patch.asc # gpg --verify kldstat.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/10/ r325867 releng/10.3/ r325878 releng/10.4/ r325877 stable/11/ r325866 releng/11.0/ r325876 releng/11.1/ r325875 - ------------------------------------------------------------------------- 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://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-1088> The latest revision of this advisory is available at <URL:https://security.FreeBSD.org/advisories/FreeBSD-SA-17:10.kldstat.asc> -----BEGIN PGP SIGNATURE----- iQKTBAEBCgB9FiEEHPf/b631yp++G4yy7Wfs1l3PaucFAloToOxfFIAAAAAALgAo aXNzdWVyLWZwckBub3RhdGlvbnMub3BlbnBncC5maWZ0aGhvcnNlbWFuLm5ldDFD RjdGRjZGQURGNUNBOUZCRTFCOENCMkVENjdFQ0Q2NURDRjZBRTcACgkQ7Wfs1l3P audl/RAAkPqcGvCMAHucBtZH2sySvM/1L1NTl0I61eJaDqgnjooo3hRq5J/dlNlt zo48o2W0EOnr8QWJhVg1oADY5qxBVm8RldpAH1Y7lU1Pk1gw6buTvmlat9Y0TaRm i3WCYe/yzC9X50x12dSu2QCeir+HDHrHB72KQDxPJak21e8BKq8vSq4cV3+K32IF MmC0yTkwXM7JJti1wkztiNSwvcCT5cI0EOZrHxDOJk57zhmuUw3t+42mr4uZhLpd Um/Hmqt3TS1LlL/swCcayeJGI5lrnfnIMZEUJj9aJZcRry6xrtaeppvgm3rP8Bym IYBipTU16MGVU6PEdpxXZCkmhzrb5XkAHNnRbod/Ye4g5a+3tWeaivjxbrNRsJyc 7HkuvW41LX1+hJ2DJ/IJGKhz0yP+7//pXNJIkcF1iKOVnVIxz+49KPjj3ZHYhGu2 oI/w4EMTd4ODXmE+bZkwGGm3nbxlH3AIZmBL2x1MdmfO/NjUlB3tYupZ7K/wR/PD V0OdrZTua7EpYSUDg04xuNkkxRwFMIVQ3XtE1HNCuV0BtQqZOcecKh9Alci5ZT6n r+F3HhFthNsafwdXLka5zDev/qtSSxggZ75fj+BxPfCoQZSlYkegFg/9K1hXlE+c H22TsCXMpLokZUKj2XKJQ8RsEZQ5Yr6wEFjsWHoeK5CPh/DyAYE=dgLX -----END PGP SIGNATURE-----