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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2009.1368 Devfs / VFS NULL pointer race condition 5 October 2009 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: devfs Publisher: FreeBSD Operating System: FreeBSD Impact/Access: Execute Arbitrary Code/Commands -- Existing Account Increased Privileges -- Existing Account Resolution: Patch/Upgrade Original Bulletin: ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-09:14.devfs.asc - --------------------------BEGIN INCLUDED TEXT-------------------- - -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 ============================================================================= FreeBSD-SA-09:14.devfs Security Advisory The FreeBSD Project Topic: Devfs / VFS NULL pointer race condition Category: core Module: kern Announced: 2009-10-02 Credits: Przemyslaw Frasunek Affects: FreeBSD 6.x and 7.x Corrected: 2009-05-18 10:41:59 UTC (RELENG_7, 7.2-STABLE) 2009-10-02 18:09:56 UTC (RELENG_7_2, 7.2-RELEASE-p4) 2009-10-02 18:09:56 UTC (RELENG_7_1, 7.1-RELEASE-p8) 2009-10-02 18:09:56 UTC (RELENG_6, 6.4-STABLE) 2009-10-02 18:09:56 UTC (RELENG_6_4, 6.4-RELEASE-p7) 2009-10-02 18:09:56 UTC (RELENG_6_3, 6.3-RELEASE-p13) For general information regarding FreeBSD Security Advisories, including descriptions of the fields above, security branches, and the following sections, please visit <URL:http://security.FreeBSD.org/>. I. Background The device file system (devfs) provides access to system devices, such as storage devices and serial ports, via the file system namespace. VFS is the Virtual File System, which abstracts file system operations in the kernel from the actual underlying file system. II. Problem Description Due to the interaction between devfs and VFS, a race condition exists where the kernel might dereference a NULL pointer. III. Impact Successful exploitation of the race condition can lead to local kernel privilege escalation, kernel data corruption and/or crash. To exploit this vulnerability, an attacker must be able to run code with user privileges on the target system. IV. Workaround An errata note, FreeBSD-EN-09:05.null has been released simultaneously to this advisory, and contains a kernel patch implementing a workaround for a more broad class of vulnerabilities. However, prior to those changes, no workaround is available. V. Solution Perform one of the following: 1) Upgrade your vulnerable system to 6-STABLE, or 7-STABLE, or to the RELENG_7_2, RELENG_7_1, RELENG_6_4, or RELENG_6_3 security branch dated after the correction date. 2) To patch your present system: The following patches have been verified to apply to FreeBSD 6.3, 6.4, 7.1, and 7.2 systems. a) Download the relevant patch from the location below, and verify the detached PGP signature using your PGP utility. [FreeBSD 6.x] # fetch http://security.FreeBSD.org/patches/SA-09:14/devfs6.patch # fetch http://security.FreeBSD.org/patches/SA-09:14/devfs6.patch.asc [FreeBSD 7.x] # fetch http://security.FreeBSD.org/patches/SA-09:14/devfs7.patch # fetch http://security.FreeBSD.org/patches/SA-09:14/devfs7.patch.asc b) Apply the patch. # 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. VI. Correction details The following list contains the revision numbers of each file that was corrected in FreeBSD. CVS: Branch Revision Path - - ------------------------------------------------------------------------- RELENG_6 src/sys/fs/devfs/devfs_vnops.c 1.114.2.17 RELENG_6_4 src/UPDATING 1.416.2.40.2.11 src/sys/conf/newvers.sh 1.69.2.18.2.13 src/sys/fs/devfs/devfs_vnops.c 1.114.2.16.2.2 RELENG_6_3 src/UPDATING 1.416.2.37.2.18 src/sys/conf/newvers.sh 1.69.2.15.2.17 src/sys/fs/devfs/devfs_vnops.c 1.114.2.15.2.1 RELENG_7 src/sys/fs/devfs/devfs_vnops.c 1.149.2.9 RELENG_7_2 src/UPDATING 1.507.2.23.2.7 src/sys/conf/newvers.sh 1.72.2.11.2.8 src/sys/fs/devfs/devfs_vnops.c 1.149.2.8.2.2 RELENG_7_1 src/UPDATING 1.507.2.13.2.11 src/sys/conf/newvers.sh 1.72.2.9.2.12 src/sys/fs/devfs/devfs_vnops.c 1.149.2.4.2.2 - - ------------------------------------------------------------------------- Subversion: Branch/path Revision - - ------------------------------------------------------------------------- stable/6/ r197715 releng/6.4/ r197715 releng/6.3/ r197715 stable/7/ r192301 releng/7.2/ r197715 releng/7.1/ r197715 - - ------------------------------------------------------------------------- VII. References The latest revision of this advisory is available at http://security.FreeBSD.org/advisories/FreeBSD-SA-09:14.devfs.asc - -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10 (FreeBSD) iD8DBQFKxltlFdaIBMps37IRAp4zAJwJEwIySGqxH4EXwc0wjkDXlcTb1wCfTltO Syds53GSM0YbsMNUVMGsLaU= =exPZ - -----END PGP SIGNATURE----- - --------------------------END INCLUDED TEXT-------------------- You have received this e-mail bulletin as a result of your organisation's registration with AusCERT. The mailing list you are subscribed to is maintained within your organisation, so if you do not wish to continue receiving these bulletins you should contact your local IT manager. If you do not know who that is, please send an email to auscert@auscert.org.au and we will forward your request to the appropriate person. NOTE: Third Party Rights This security bulletin is provided as a service to AusCERT's members. As AusCERT did not write the document quoted above, AusCERT has had no control over its content. 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Previous advisories and external security bulletins can be retrieved from: http://www.auscert.org.au/render.html?cid=1980 If you believe that your computer system has been compromised or attacked in any way, we encourage you to let us know by completing the secure National IT Incident Reporting Form at: http://www.auscert.org.au/render.html?it=3192 =========================================================================== Australian Computer Emergency Response Team The University of Queensland Brisbane Qld 4072 Internet Email: auscert@auscert.org.au Facsimile: (07) 3365 7031 Telephone: (07) 3365 4417 (International: +61 7 3365 4417) AusCERT personnel answer during Queensland business hours which are GMT+10:00 (AEST). On call after hours for member emergencies only. =========================================================================== -----BEGIN PGP SIGNATURE----- Comment: http://www.auscert.org.au/render.html?it=1967 iD8DBQFKyTlcNVH5XJJInbgRAo0IAJ4kt6y2w4avcUnhy3osg/OS+JKyggCdEOkv GPucEHamo5sdfGqXE9oseqg= =K/Oo -----END PGP SIGNATURE-----