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-----BEGIN PGP SIGNED MESSAGE----- =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2003.0702 -- FreeBSD-SA-03:17.procfs kernel memory disclosure via procfs 06 October 2003 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: process file system Publisher: FreeBSD Operating System: FreeBSD Impact: Denial of Service Reduced Security Access Required: Existing Account - --------------------------BEGIN INCLUDED TEXT-------------------- - -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 ============================================================================= FreeBSD-SA-03:17.procfs Security Advisory The FreeBSD Project Topic: kernel memory disclosure via procfs Category: core Module: sys Announced: 2003-10-03 Credits: Joost Pol <joost@pine.nl> Affects: All FreeBSD releases Corrected: 2003-10-03 12:03:50 UTC (RELENG_4, 4.9-RC) 2003-10-03 13:02:17 UTC (RELENG_5_1, 5.1-RELEASE-p9) 2003-10-03 13:02:49 UTC (RELENG_5_0, 5.0-RELEASE-p17) 2003-10-03 13:03:44 UTC (RELENG_4_8, 4.8-RELEASE-p12) 2003-10-03 13:04:19 UTC (RELENG_4_7, 4.7-RELEASE-p22) 2003-10-03 13:05:05 UTC (RELENG_4_6, 4.6-RELEASE-p25) 2003-10-03 13:05:44 UTC (RELENG_4_5, 4.5-RELEASE-p36) 2003-10-03 13:06:32 UTC (RELENG_4_4, 4.4-RELEASE-p46) 2003-10-03 13:07:37 UTC (RELENG_4_3, 4.3-RELEASE-p42) FreeBSD only: YES 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 process file system, procfs(5), implements a view of the system process table inside the file system. It is normally mounted on /proc, and is required for the complete operation of programs such as ps(1) and w(1). The Linux process file system, linprocfs(5), emulates a subset of Linux's process file system and is required for the complete operation of some Linux binaries. II. Problem Description The procfs and linprocfs implementations use uiomove(9) and the related `struct uio' in order to fulfill read and write requests. Several cases were identified where members of `struct uio' were not properly validated before being used. In particular, the `uio_offset' member may be negative or extremely large, and was used to compute the region of kernel memory to be returned to the user. III. Impact A malicious local user could arrange to use a negative or extremely large offset when reading from a procfs ``file'', causing a system crash, or causing the kernel to return a large portion of kernel memory. Such memory might contain sensitive information, such as portions of the file cache or terminal buffers. This information might be directly useful, or it might be leveraged to obtain elevated privileges in some way. For example, a terminal buffer might include a user-entered password. IV. Workaround Unmount the procfs and linprocfs filesystems if they are mounted. Execute the following command as root: umount -a -t procfs,linprocfs Also, remove or comment out any lines in fstab(5) that reference `procfs' or `linprocfs', so that they will not be re-mounted at next reboot. V. Solution 1) Upgrade your vulnerable system to 4-STABLE, or to the RELENG_5_1, RELENG_4_8, or RELENG_4_7 security branch dated after the correction date. 2) To patch your present system: a) Download the relevant patch from the location below, and verify the detached PGP signature using your PGP utility. [FreeBSD 4.3] # fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-03:17/procfs43.patch # fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-03:17/procfs43.patch.asc [FreeBSD 4.4 and later 4.x] # fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-03:17/procfs4x.patch # fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-03:17/procfs4x.patch.asc [FreeBSD 5.0] # fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-03:17/procfs50.patch # fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-03:17/procfs50.patch.asc [FreeBSD 5.1] # fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-03:17/procfs51.patch # fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-03:17/procfs51.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/linux/linprocfs/linprocfs_misc.c 1.3.2.9 src/sys/kern/kern_subr.c 1.31.2.3 src/sys/miscfs/procfs/procfs_dbregs.c 1.4.2.4 src/sys/miscfs/procfs/procfs_fpregs.c 1.11.2.4 src/sys/miscfs/procfs/procfs_regs.c 1.10.2.4 src/sys/miscfs/procfs/procfs_rlimit.c 1.5.2.1 src/sys/miscfs/procfs/procfs_status.c 1.20.2.5 src/sys/sys/uio.h 1.11.2.2 RELENG_5_1 src/UPDATING 1.251.2.11 src/sys/conf/newvers.sh 1.50.2.11 src/sys/fs/procfs/procfs_dbregs.c 1.22.2.1 src/sys/fs/procfs/procfs_fpregs.c 1.28.2.1 src/sys/fs/procfs/procfs_regs.c 1.27.2.1 src/sys/fs/pseudofs/pseudofs_vnops.c 1.35.2.1 src/sys/kern/kern_subr.c 1.74.2.1 src/sys/sys/uio.h 1.27.2.1 RELENG_5_0 src/UPDATING 1.229.2.23 src/sys/conf/newvers.sh 1.48.2.18 src/sys/fs/procfs/procfs_dbregs.c 1.21.2.1 src/sys/fs/procfs/procfs_fpregs.c 1.27.2.1 src/sys/fs/procfs/procfs_regs.c 1.26.2.1 src/sys/fs/pseudofs/pseudofs_vnops.c 1.32.2.1 src/sys/kern/kern_subr.c 1.63.2.1 src/sys/sys/uio.h 1.23.2.1 RELENG_4_8 src/UPDATING 1.73.2.80.2.14 src/sys/conf/newvers.sh 1.44.2.29.2.13 src/sys/i386/linux/linprocfs/linprocfs_misc.c 1.3.2.8.10.1 src/sys/kern/kern_subr.c 1.31.2.2.6.1 src/sys/miscfs/procfs/procfs_dbregs.c 1.4.2.3.8.1 src/sys/miscfs/procfs/procfs_fpregs.c 1.11.2.3.8.1 src/sys/miscfs/procfs/procfs_regs.c 1.10.2.3.8.1 src/sys/miscfs/procfs/procfs_rlimit.c 1.5.14.1 src/sys/miscfs/procfs/procfs_status.c 1.20.2.4.8.1 src/sys/sys/uio.h 1.11.2.1.8.1 RELENG_4_7 src/UPDATING 1.73.2.74.2.25 src/sys/conf/newvers.sh 1.44.2.26.2.24 src/sys/i386/linux/linprocfs/linprocfs_misc.c 1.3.2.8.8.1 src/sys/kern/kern_subr.c 1.31.2.2.4.1 src/sys/miscfs/procfs/procfs_dbregs.c 1.4.2.3.6.1 src/sys/miscfs/procfs/procfs_fpregs.c 1.11.2.3.6.1 src/sys/miscfs/procfs/procfs_regs.c 1.10.2.3.6.1 src/sys/miscfs/procfs/procfs_rlimit.c 1.5.12.1 src/sys/miscfs/procfs/procfs_status.c 1.20.2.4.6.1 src/sys/sys/uio.h 1.11.2.1.6.1 RELENG_4_6 src/UPDATING 1.73.2.68.2.54 src/sys/conf/newvers.sh 1.44.2.23.2.42 src/sys/i386/linux/linprocfs/linprocfs_misc.c 1.3.2.8.6.1 src/sys/kern/kern_subr.c 1.31.2.2.2.1 src/sys/miscfs/procfs/procfs_dbregs.c 1.4.2.3.4.1 src/sys/miscfs/procfs/procfs_fpregs.c 1.11.2.3.4.1 src/sys/miscfs/procfs/procfs_regs.c 1.10.2.3.4.1 src/sys/miscfs/procfs/procfs_rlimit.c 1.5.10.1 src/sys/miscfs/procfs/procfs_status.c 1.20.2.4.4.1 src/sys/sys/uio.h 1.11.2.1.4.1 RELENG_4_5 src/UPDATING 1.73.2.50.2.53 src/sys/conf/newvers.sh 1.44.2.20.2.37 src/sys/i386/linux/linprocfs/linprocfs_misc.c 1.3.2.8.4.1 src/sys/kern/kern_subr.c 1.31.2.1.2.1 src/sys/miscfs/procfs/procfs_dbregs.c 1.4.2.3.2.1 src/sys/miscfs/procfs/procfs_fpregs.c 1.11.2.3.2.1 src/sys/miscfs/procfs/procfs_regs.c 1.10.2.3.2.1 src/sys/miscfs/procfs/procfs_rlimit.c 1.5.8.1 src/sys/miscfs/procfs/procfs_status.c 1.20.2.4.2.1 src/sys/sys/uio.h 1.11.2.1.2.1 RELENG_4_4 src/UPDATING 1.73.2.43.2.54 src/sys/conf/newvers.sh 1.44.2.17.2.45 src/sys/i386/linux/linprocfs/linprocfs_misc.c 1.3.2.8.2.1 src/sys/kern/kern_subr.c 1.31.6.1 src/sys/miscfs/procfs/procfs_dbregs.c 1.4.2.2.2.2 src/sys/miscfs/procfs/procfs_fpregs.c 1.11.2.2.2.2 src/sys/miscfs/procfs/procfs_regs.c 1.10.2.2.2.2 src/sys/miscfs/procfs/procfs_rlimit.c 1.5.6.1 src/sys/miscfs/procfs/procfs_status.c 1.20.2.3.4.2 src/sys/sys/uio.h 1.11.6.1 RELENG_4_3 src/UPDATING 1.73.2.28.2.41 src/sys/conf/newvers.sh 1.44.2.14.2.31 src/sys/i386/linux/linprocfs/linprocfs_misc.c 1.3.2.5.2.1 src/sys/kern/kern_subr.c 1.31.4.1 src/sys/miscfs/procfs/procfs_dbregs.c 1.4.2.1.2.2 src/sys/miscfs/procfs/procfs_fpregs.c 1.11.2.1.2.2 src/sys/miscfs/procfs/procfs_regs.c 1.10.2.1.2.2 src/sys/miscfs/procfs/procfs_rlimit.c 1.5.4.1 src/sys/miscfs/procfs/procfs_status.c 1.20.2.3.2.2 src/sys/sys/uio.h 1.11.4.1 - - ------------------------------------------------------------------------- VII. References <URL:http://www.pine.nl/press/pine-cert-20030902.txt> - -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.3 (FreeBSD) iD8DBQE/fYXyFdaIBMps37IRArbkAJ4qv/N215x61BW2NTyl6e4WY/DGLACgirQd evgz6IOFh0L8fLRBHjbKO4A= =Np7P - -----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. 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 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 iQCVAwUBP4CwBSh9+71yA2DNAQFc0wP+K2ZyV6LHVbEda8aGTV+bs9zgTc0B5dEP 5Bpj9dp5iGkeNWty/ZcF4+JkNefWfxqK29VuOIDQZ9jzJ+kAfqLFs1otYqgVE0Sb ightZVUB13/F4ZVX8Y3WVW4xhRwxx1Uf58gm88/gWtptmJYaupTsDU2ZOIdi4Zuk aVlj8/CzUTg= =pvL/ -----END PGP SIGNATURE-----