===================================================================== CERT-Renater Note d'Information No. 2005/VULN238 _____________________________________________________________________ DATE : 06/04/2005 HARDWARE PLATFORM(S) : / OPERATING SYSTEM(S) : FreeBSD 4.x, FreeBSD 5.x. ====================================================================== ============================================================================= FreeBSD-SA-05:02.sendfile Security Advisory The FreeBSD Project Topic: sendfile kernel memory disclosure Category: core Module: sys_kern Announced: 2005-04-04 Credits: Sven Berkvens Marc Olzheim Affects: All FreeBSD 4.x releases All FreeBSD 5.x releases prior to 5.4-RELEASE Corrected: 2005-04-04 23:52:02 UTC (RELENG_5, 5.4-STABLE) 2005-04-04 23:52:35 UTC (RELENG_5_4, 5.4-RELEASE) 2005-04-04 23:53:24 UTC (RELENG_5_3, 5.3-RELEASE-p7) 2005-04-04 23:53:36 UTC (RELENG_4, 4.11-STABLE) 2005-04-04 23:53:56 UTC (RELENG_4_11, 4.11-RELEASE-p2) 2005-04-04 23:54:13 UTC (RELENG_4_10, 4.10-RELEASE-p7) 2005-04-04 23:54:33 UTC (RELENG_4_8, 4.8-RELEASE-p29) CVE Name: CAN-2005-0708 For general information regarding FreeBSD Security Advisories, including descriptions of the fields above, security branches, and the following sections, please visit . I. Background The sendfile(2) system call allows a server application (such as an HTTP or FTP server) to transmit the contents of a file over a network connection without first copying it to application memory. High performance servers such as Apache and ftpd use sendfile. II. Problem Description If the file being transmitted is truncated after the transfer has started but before it completes, sendfile(2) will transfer the contents of more or less random portions of kernel memory in lieu of the missing part of the file. III. Impact A local user could create a large file and truncate it while transferring it to himself, thus obtaining a copy of portions of system memory to which he would normally not have access. 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 No known workaround. V. Solution Perform one of the following: 1) Upgrade your vulnerable system to 4-STABLE or 5-STABLE, or to the RELENG_5_3, RELENG_4_11, RELENG_4_10, or RELENG_4_8 security branch dated after the correction date. 2) To patch your present system: The following patches have been verified to apply to FreeBSD 4.8, 4.10, 4.11, and 5.3 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-05:02/sendfile_4.patch # fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-05:02/sendfile_4.patch.asc [FreeBSD 5.3] # fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-05:02/sendfile_5.patch # fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-05:02/sendfile_5.patch.asc b) Apply the patch. # cd /usr/src # patch < /path/to/patch c) Recompile your kernel as described in 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/ufs/ffs/ffs_inode.c 1.56.2.6 RELENG_4_11 src/UPDATING 1.73.2.91.2.3 src/sys/conf/newvers.sh 1.44.2.39.2.6 src/sys/ufs/ffs/ffs_inode.c 1.56.2.5.12.1 RELENG_4_10 src/UPDATING 1.73.2.90.2.8 src/sys/conf/newvers.sh 1.44.2.34.2.8 src/sys/ufs/ffs/ffs_inode.c 1.56.2.5.10.1 RELENG_4_8 src/UPDATING 1.73.2.80.2.33 src/sys/conf/newvers.sh 1.44.2.29.2.29 src/sys/ufs/ffs/ffs_inode.c 1.56.2.5.6.1 RELENG_5 src/sys/ufs/ffs/ffs_inode.c 1.93.2.2 RELENG_5_4 src/UPDATING 1.342.2.24.2.1 src/sys/ufs/ffs/ffs_inode.c 1.93.2.1.2.1 RELENG_5_3 src/UPDATING 1.342.2.13.2.10 src/sys/conf/newvers.sh 1.62.2.15.2.12 src/sys/ufs/ffs/ffs_inode.c 1.93.4.1 - - ------------------------------------------------------------------------- The latest revision of this advisory is available at ftp://ftp.freebsd.org/pub/CERT/advisories/FreeBSD-SA-05:02.sendfile.asc ====================================================================== ========================================================= Les serveurs de référence du CERT-Renater http://www.urec.fr/securite http://www.cru.fr/securite http://www.renater.fr ========================================================= + CERT-RENATER | tel : 01-53-94-20-44 + + 151 bd de l'Hopital | fax : 01-53-94-20-41 + + 75013 Paris | email: certsvp@renater.fr + =========================================================