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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2009.0298 -- [FreeBSD] kernel: Denial of Service 30 March 2009 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: kern Publisher: FreeBSD Operating System: FreeBSD Impact: Denial of Service Access: Existing Account Original Bulletin: http://security.freebsd.org/advisories/FreeBSD-EN-09:01.kenv.asc - --------------------------BEGIN INCLUDED TEXT-------------------- - -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 ============================================================================= FreeBSD-EN-09:01.kenv Errata Notice The FreeBSD Project Topic: Kernel panic when dumping environment Category: core Module: kern Announced: 2009-03-23 Affects: FreeBSD 7.x Corrected: 2009-03-23 00:00:50 UTC (RELENG_7, 7.2-PRERELEASE) 2009-03-23 00:00:50 UTC (RELENG_7_1, 7.1-RELEASE-p4) 2009-03-23 00:00:50 UTC (RELENG_7_0, 7.0-RELEASE-p11) 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 kenv(2) system call allows userland processes to get, set, and unset kernel environment variables, as well as to dump all of the entries in the kernel environment. II. Problem Description When dumping all of the entries in the kernel environment, the kernel does not adequately bounds-check the size of the buffer into which the environment should be written. III. Impact An unprivileged process can cause the FreeBSD kernel to attempt to allocate a very large amount of memory, thereby causing the FreeBSD kernel to panic. IV. Workaround No workaround is available, but systems without untrusted local users are not vulnerable. V. Solution Perform one of the following: 1) Upgrade your vulnerable system to 7-STABLE, or to the RELENG_7_1 or RELENG_7_0 security branch dated after the correction date. 2) To patch your present system: The following patch has been verified to apply to FreeBSD 7.0 and 7.1 systems. a) Download the patch from the location below, and verify the detached PGP signature using your PGP utility. # fetch http://security.FreeBSD.org/patches/EN-09:01/kenv.patch # fetch http://security.FreeBSD.org/patches/EN-09:01/kenv.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_7 src/sys/kern/kern_environment.c 1.47.2.1 RELENG_7_1 src/UPDATING 1.507.2.13.2.7 src/sys/conf/newvers.sh 1.72.2.9.2.8 src/sys/kern/kern_environment.c 1.47.6.2 RELENG_7_0 src/UPDATING 1.507.2.3.2.15 src/sys/conf/newvers.sh 1.72.2.5.2.15 src/sys/kern/kern_environment.c 1.47.4.1 - - ------------------------------------------------------------------------- Subversion: Branch/path Revision - - ------------------------------------------------------------------------- stable/7/ r190301 releng/7.1/ r190301 releng/7.0/ r190301 - - ------------------------------------------------------------------------- VII. References The latest revision of this advisory is available at http://security.FreeBSD.org/advisories/FreeBSD-EN-09:01.kenv.asc - -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (FreeBSD) iEUEARECAAYFAknG0gwACgkQFdaIBMps37ILlwCfcbVKW5FlPK+GtATY34wfkDWr 5tAAmMteIrkXAeBgp3QNI6pFiHzgunE= =wJeF - -----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. The decision to follow or act on information or advice contained in this security bulletin is the responsibility of each user or organisation, and should be considered in accordance with your organisation's site policies and procedures. AusCERT takes no responsibility for consequences which may arise from following or acting on information or advice contained in this security bulletin. NOTE: This is only the original release of the security bulletin. It may not be updated when updates to the original are made. If downloading at a later date, it is recommended that the bulletin is retrieved directly from the author's website to ensure that the information is still current. Contact information for the authors of the original document is included in the Security Bulletin above. If you have any questions or need further information, please contact them directly. 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 iD8DBQFJ0F0LNVH5XJJInbgRAvYaAJ47UN99nxRpyR6kAFJlDlQdNON44wCeJpr1 HZISDiJqUSQV5uHKMP1iHpM= =VDym -----END PGP SIGNATURE-----