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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2009.0591 -- [FreeBSD] pipe implementation: Access Privileged Data 22 June 2009 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: FreeBSD 7.1 through 7.2 FreeBSD 6.3 through 6.4 Publisher: FreeBSD Operating System: FreeBSD Impact: Access Privileged Data Access: Existing Account CVE Names: CVE-2009-1935 Original Bulletin: http://security.freebsd.org/advisories/FreeBSD-SA-09:09.pipe.asc - --------------------------BEGIN INCLUDED TEXT-------------------- ============================================================================= FreeBSD-SA-09:09.pipe Security Advisory The FreeBSD Project Topic: Local information disclosure via direct pipe writes Category: core Module: kern Announced: 2009-06-10 Credits: Pieter de Boer Affects: All supported versions of FreeBSD. Corrected: 2009-06-10 10:31:11 UTC (RELENG_7, 7.2-STABLE) 2009-06-10 10:31:11 UTC (RELENG_7_2, 7.2-RELEASE-p1) 2009-06-10 10:31:11 UTC (RELENG_7_1, 7.1-RELEASE-p6) 2009-06-10 10:31:11 UTC (RELENG_6, 6.4-STABLE) 2009-06-10 10:31:11 UTC (RELENG_6_4, 6.4-RELEASE-p5) 2009-06-10 10:31:11 UTC (RELENG_6_3, 6.3-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 One of the most commonly used forms of interprocess communication on FreeBSD and other UNIX-like systems is the (anonymous) pipe. In this mechanism, a pair of file descriptors is created, and data written to one descriptor can be read from the other. FreeBSD's pipe implementation contains an optimization known as "direct writes". In this optimization, rather than copying data into kernel memory when the write(2) system call is invoked and then copying the data again when the read(2) system call is invoked, the FreeBSD kernel takes advantage of virtual memory mapping to allow the data to be copied directly between processes. II. Problem Description An integer overflow in computing the set of pages containing data to be copied can result in virtual-to-physical address lookups not being performed. III. Impact An unprivileged process can read pages of memory which belong to other processes or to the kernel. These may contain information which is sensitive in itself; or may contain passwords or cryptographic keys which can be indirectly exploited to gain sensitive information or access. IV. Workaround No workaround is available, but systems without untrusted local users are not vulnerable. System administrators are reminded that even if a system is not intended to have untrusted local users, it may be possible for an attacker to exploit some other vulnerability to obtain local user access to a system. 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. # fetch http://security.FreeBSD.org/patches/SA-09:09/pipe.patch # fetch http://security.FreeBSD.org/patches/SA-09:09/pipe.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/kern/sys_pipe.c 1.184.2.5 RELENG_6_4 src/UPDATING 1.416.2.40.2.9 src/sys/conf/newvers.sh 1.69.2.18.2.11 src/sys/kern/sys_pipe.c 1.184.2.4.2.2 RELENG_6_3 src/UPDATING 1.416.2.37.2.16 src/sys/conf/newvers.sh 1.69.2.15.2.15 src/sys/kern/sys_pipe.c 1.184.2.2.6.2 RELENG_7 src/sys/kern/sys_pipe.c 1.191.2.5 RELENG_7_2 src/UPDATING 1.507.2.23.2.4 src/sys/conf/newvers.sh 1.72.2.11.2.5 src/sys/kern/sys_pipe.c 1.191.2.3.4.2 RELENG_7_1 src/UPDATING 1.507.2.13.2.9 src/sys/conf/newvers.sh 1.72.2.9.2.10 src/sys/kern/sys_pipe.c 1.191.2.3.2.2 - - ------------------------------------------------------------------------- Subversion: Branch/path Revision - - ------------------------------------------------------------------------- stable/6/ r193893 releng/6.4/ r193893 releng/6.3/ r193893 stable/7/ r193893 releng/7.2/ r193893 releng/7.1/ r193893 - - ------------------------------------------------------------------------- VII. References The latest revision of this advisory is available at http://security.FreeBSD.org/advisories/FreeBSD-SA-09:09.pipe.asc - --------------------------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 iD8DBQFKPwOTNVH5XJJInbgRArQfAJ4hv9iB1xgz7Y3syajkxO69UmZUXQCfR+dt Am5CRZt6sTlVAPD3+VBe3OM= =IvH/ -----END PGP SIGNATURE-----