Protect yourself against future threats.
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2006.0272 -- [FreeBSD] FPU information disclosure 20 April 2006 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: kernel Publisher: FreeBSD Operating System: FreeBSD 4.10, 4.11, 5.3, 5.4, 6.0 Platform: AMD Athlon Duron Athlon MP Athlon XP Athlon64 Athlon64 FX Opteron Turion Sempron Impact: Access Confidential Data Access: Existing Account CVE Names: CVE-2006-1056 Original Bulletin: ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-06:14.fpu.asc - --------------------------BEGIN INCLUDED TEXT-------------------- - -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 ============================================================================= FreeBSD-SA-06:14.fpu Security Advisory The FreeBSD Project Topic: FPU information disclosure Category: core Module: sys Announced: 2006-04-19 Credits: Jan Beulich Affects: All FreeBSD/i386 and FreeBSD/amd64 releases. Corrected: 2006-04-19 07:00:35 UTC (RELENG_6, 6.1-STABLE) 2006-04-19 07:00:50 UTC (RELENG_6_1, 6.1-RELEASE) 2006-04-19 07:01:12 UTC (RELENG_6_0, 6.0-RELEASE-p7) 2006-04-19 07:01:30 UTC (RELENG_5, 5.5-STABLE) 2006-04-19 07:01:53 UTC (RELENG_5_4, 5.4-RELEASE-p14) 2006-04-19 07:02:23 UTC (RELENG_5_3, 5.3-RELEASE-p29) 2006-04-19 07:02:43 UTC (RELENG_4, 4.11-STABLE) 2006-04-19 07:03:01 UTC (RELENG_4_11, 4.11-RELEASE-p17) 2006-04-19 07:03:14 UTC (RELENG_4_10, 4.10-RELEASE-p23) CVE Name: CVE-2006-1056 For general information regarding FreeBSD Security Advisories, including descriptions of the fields above, security branches, and the following sections, please visit <URL:http://www.freebsd.org/security/>. I. Background The floating-point unit (FPU) of i386 and amd64 processors is derived from the original 8087 floating-point co-processor. As a result, the FPU contains the same debugging registers FOP, FIP, and FDP which store the opcode, instruction address, and data address of the instruction most recently executed by the FPU. On processors implementing the "SSE" instruction set, a new pair of instructions fxsave/fxrstor replaces the earlier fsave/frstor pair used for saving and restoring the FPU state. These new instructions also save and restore the contents of the additional registers used by SSE instructions. II. Problem Description On "7th generation" and "8th generation" processors manufactured by AMD, including the AMD Athlon, Duron, Athlon MP, Athlon XP, Athlon64, Athlon64 FX, Opteron, Turion, and Sempron, the fxsave and fxrstor instructions do not save and restore the FOP, FIP, and FDP registers unless the exception summary bit (ES) in the x87 status word is set to 1, indicating that an unmasked x87 exception has occurred. This behaviour is consistent with documentation provided by AMD, but is different from processors from other vendors, which save and restore the FOP, FIP, and FDP registers regardless of the value of the ES bit. As a result of this discrepancy remaining unnoticed until now, the FreeBSD kernel does not restore the contents of the FOP, FIP, and FDP registers between context switches. III. Impact On affected processors, a local attacker can monitor the execution path of a process which uses floating-point operations. This may allow an attacker to steal cryptographic keys or other sensitive information. IV. Workaround No workaround is available, but systems which do not use AMD Athlon, Duron, Athlon MP, Athlon XP, Athlon64, Athlon64 FX, Opteron, Turion, or Sempron processors are not vulnerable. V. Solution Perform one of the following: 1) Upgrade your vulnerable system to 4-STABLE, 5-STABLE, or 6-STABLE, or to the RELENG_6_0, RELENG_5_4, RELENG_5_3, RELENG_4_11, or RELENG_4_10 security branch dated after the correction date. 2) To patch your present system: The following patches have been verified to apply to FreeBSD 4.10, 4.11, 5.3, 5.4, and 6.0 systems. a) Download the relevant patch from the location below, and verify the detached PGP signature using your PGP utility. [FreeBSD 4.x] # fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-06:14/fpu4x.patch # fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-06:14/fpu4x.patch.asc [FreeBSD 5.x and 6.x] # fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-06:14/fpu.patch # fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-06:14/fpu.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. Branch Revision Path - - ------------------------------------------------------------------------- RELENG_4 src/sys/i386/isa/npx.c 1.80.2.4 RELENG_4_11 src/UPDATING 1.73.2.91.2.18 src/sys/conf/newvers.sh 1.44.2.39.2.21 src/sys/i386/isa/npx.c 1.80.2.3.14.1 RELENG_4_10 src/UPDATING 1.73.2.90.2.24 src/sys/conf/newvers.sh 1.44.2.34.2.25 src/sys/i386/isa/npx.c 1.80.2.3.12.1 RELENG_5 src/sys/amd64/amd64/fpu.c 1.154.2.2 src/sys/i386/isa/npx.c 1.152.2.4 RELENG_5_4 src/UPDATING 1.342.2.24.2.23 src/sys/conf/newvers.sh 1.62.2.18.2.19 src/sys/amd64/amd64/fpu.c 1.154.2.1.2.1 src/sys/i386/isa/npx.c 1.152.2.3.2.1 RELENG_5_3 src/UPDATING 1.342.2.13.2.32 src/sys/conf/newvers.sh 1.62.2.15.2.34 src/sys/amd64/amd64/fpu.c 1.154.4.1 src/sys/i386/isa/npx.c 1.152.4.1 RELENG_6 src/sys/amd64/amd64/fpu.c 1.157.2.1 src/sys/i386/isa/npx.c 1.162.2.2 RELENG_6_1 src/UPDATING 1.416.2.22.2.1 src/sys/conf/newvers.sh 1.69.2.11.2.1 src/sys/amd64/amd64/fpu.c 1.157.6.1 src/sys/i386/isa/npx.c 1.162.2.1.2.1 RELENG_6_0 src/UPDATING 1.416.2.3.2.12 src/sys/conf/newvers.sh 1.69.2.8.2.8 src/sys/amd64/amd64/fpu.c 1.157.4.1 src/sys/i386/isa/npx.c 1.162.4.1 - - ------------------------------------------------------------------------- VII. References http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-1056 The latest revision of this advisory is available at ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-06:14.fpu.asc VIII. Acknowledgements The FreeBSD Security Team would like to thank AMD, and Richard Brunner specifically, for responding promptly to this issue and providing an extensive response analyzing the problem. - -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.3 (FreeBSD) iD8DBQFEReGUFdaIBMps37IRAnmUAJ4lsl3bpH6duA5u/wssIa01o98BlwCgleWn a1vJCiLwkkfqHtmBDKxaQ+A= =4yls - -----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 iQCVAwUBREbAUCh9+71yA2DNAQJedAP/RZ0YaT3GCLp00udoqyxhl8hMrLHFIkgn hIrF4pR5Ga/hgrGCDW9iXPy9/1Wy96CKDziltUp6CBsjHKkWVFW80T6p9o4/QpIi vpEleIpuVisBvcefFNw9cmlfPEYZ7nTskh6dqgSTQAU7stb5mdM67uv7T1A0gJNB C0I4oCXyrlE= =vvn6 -----END PGP SIGNATURE-----