3571e53040
patches for easier mirroring, to eliminate a special copy, to make www.freebsd.org/security a full copy of security.freebsd.org and be eventually be the same. For now files are just sitting there. The symlinks are missing. Discussed on: www (repository location) Discussed with: simon (so)
171 lines
6.5 KiB
Text
171 lines
6.5 KiB
Text
-----BEGIN PGP SIGNED MESSAGE-----
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=============================================================================
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FreeBSD-SA-02:18 Security Advisory
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FreeBSD, Inc.
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Topic: zlib double-free
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Category: core, ports
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Module: zlib
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Announced: 2002-03-18
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Revised: 2002-04-22
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Credits: Matthias Clasen <maclas@gmx.de>
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Owen Taylor <otaylor@redhat.com>
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Affects: All released versions of FreeBSD
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FreeBSD 4.5-STABLE prior to the correction date
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Various ports using or including zlib
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Corrected: 2002-02-24 23:12:48 UTC (RELENG_4)
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2002-02-24 23:22:57 UTC (RELENG_4_5)
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2002-02-24 23:23:58 UTC (RELENG_4_4)
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2002-02-24 23:24:46 UTC (RELENG_4_3)
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CVE: CAN-2002-0059
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FreeBSD only: NO
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0. Revision History
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v1.0 2002-03-18 Initial release
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v1.1 2002-04-18 Corrected ZFREE location in kernel patch
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Corrected deflate window size check
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v1.2 2002-04-22 Corrected advisory revision dates.
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I. Background
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zlib is a compression library used by numerous applications to provide
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data compression/decompression routines.
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II. Problem Description
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A programming error in zlib may cause segments of dynamically
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allocated memory to be released more than once (double-freed).
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If an attacker is able to pass a specially-crafted block of invalid
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compressed data to a program that includes zlib, the program's
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attempt to decompress the crafted data may cause the zlib routines
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to attempt to free memory multiple times.
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Unlike some implementations of malloc(3)/free(3), the malloc(3) and
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free(3) routines used in FreeBSD (aka phkmalloc, written by
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Poul-Henning Kamp <phk@FreeBSD.org>), are not vulnerable to this type
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of bug. From the author:
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Most mallocs keep their housekeeping data right next to the
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allocated range. This gives rise to all sorts of unpleassant
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situations if programs stray outside the dotted line, free(3)
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things twice or free(3) modified pointers.
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phkmalloc(3) does not store housekeeping next to allocated data,
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and in particular it has code that detects and complains about
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exactly this kind of double free.
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When attempting to double-free an area of memory, phkmalloc will
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issue a warning:
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progname in free(): error: chunk is already free
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and may call abort(3) if the malloc flag 'A' is used.
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III. Impact
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If an attacker is able to pass a specially-crafted block of invalid
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compressed data to an application that utilizes zlib, the attempt to
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decompress the data may cause incorrect operation of the application,
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including possibly crashing the application. Also, the malloc
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implementation will issue warnings and, if the `A' malloc option is
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used, cause the application to abort(3). In short, an attacker may
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cause a denial of service in applications utilizing zlib.
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IV. Workaround
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To prevent affected programs from aborting, remove the 'A' from
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the malloc flags. To check which malloc flags are in use, issue the
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following commands:
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# ls -l /etc/malloc.conf
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# echo $MALLOC_OPTIONS
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A nonexistent /etc/malloc.conf or MALLOC_OPTIONS environmental variable
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means that no malloc flags are in use. See the malloc(3) man page for
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more information.
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V. Solution
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[FreeBSD 4.x base system]
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1) Upgrade your vulnerable system to 4.5-STABLE or to one of the
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RELENG_4_4 or RELENG_4_5 security branches dated after the respective
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correction dates.
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2) To patch your present system: download the relevant patch from the
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below location, and execute the following commands as root:
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For FreeBSD 4.x systems that have the previous zlib patch applied:
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# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-02:18/zlib.v1.1.corrected.patch
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# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-02:18/zlib.v1.1.corrected.patch.asc
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For FreeBSD 4.x systems that do not have the previous zlib patch
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applied:
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# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-02:18/zlib.v1.1.patch
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# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-02:18/zlib.v1.1.patch.asc
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Verify the detached PGP signature using your PGP utility.
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This patch has been verified to apply to all FreeBSD 4.x versions.
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# cd /usr/src
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# patch -p < /path/to/patch
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# cd lib/libz
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# make depend && make all install
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Then rebuild and reinstall your kernel as described in
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http://www.freebsd.org/handbook/kernelconfig.html and reboot the
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system with the new kernel for the changes to take effect.
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[ports]
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Various ports may statically link zlib or contain their own versions
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of zlib that have not been corrected by updating the FreeBSD libz.
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Efforts are underway to identify and correct these ports.
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VI. Correction details
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The following list contains the revision numbers of each file that was
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corrected in FreeBSD.
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Path Revision
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Branch
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- -------------------------------------------------------------------------
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src/lib/libz/deflate.c
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RELENG_4 1.5.2.1
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RELENG_4_5 1.5.8.1
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RELENG_4_4 1.5.6.1
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RELENG_4_3 1.5.4.1
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src/lib/libz/infblock.c
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RELENG_4 1.1.1.4.6.1
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RELENG_4_5 1.1.1.4.12.1
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RELENG_4_4 1.1.1.4.10.1
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RELENG_4_3 1.1.1.4.8.1
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src/sys/net/zlib.c
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RELENG_4 1.10.2.3
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RELENG_4_5 1.10.8.2
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RELENG_4_4 1.10.6.2
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RELENG_4_3 1.10.4.2
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- -------------------------------------------------------------------------
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VII. References
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<URL:http://online.securityfocus.com/archive/1/261205>
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The Common Vulnerabilities and Exposures project (cve.mitre.org) has
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assigned the name CAN-2002-0059 to this issue.
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-----BEGIN PGP SIGNATURE-----
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Version: GnuPG v1.0.6 (FreeBSD)
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Comment: For info see http://www.gnupg.org
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-----END PGP SIGNATURE-----
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