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)
197 lines
8.6 KiB
Text
197 lines
8.6 KiB
Text
-----BEGIN PGP SIGNED MESSAGE-----
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Hash: SHA1
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=============================================================================
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FreeBSD-SA-03:09.signal Security Advisory
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The FreeBSD Project
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Topic: Insufficient range checking of signal numbers
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Category: core
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Module: sys
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Announced: 2003-08-10
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Affects: All releases of FreeBSD up to and including 4.8-RELEASE-p1,
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5.1-RELEASE (but see `Impact' below)
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FreeBSD 4-STABLE prior to the correction date
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Corrected: 2003-08-10 23:09:28 UTC (RELENG_4)
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2003-08-10 23:14:08 UTC (RELENG_5_1)
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2003-08-10 23:17:48 UTC (RELENG_5_0)
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2003-08-10 23:19:35 UTC (RELENG_4_8)
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2003-08-11 10:14:38 UTC (RELENG_4_7)
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2003-08-11 10:16:35 UTC (RELENG_4_6)
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2003-08-12 20:23:24 UTC (RELENG_4_5)
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2003-08-12 20:23:51 UTC (RELENG_4_4)
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2003-08-12 20:24:13 UTC (RELENG_4_3)
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FreeBSD only: YES
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For general information regarding FreeBSD Security Advisories,
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including descriptions of the fields above, security branches, and the
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following sections, please visit
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<URL:http://www.freebsd.org/security/>.
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0. Revision History
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v1.0 2003-08-10 Initial release
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v1.1 2003-08-11 Updated correction details for RELENG_4_7,
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RELENG_4_6, RELENG_4_5, RELENG_4_4, RELENG_4_3
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branches. Corrected an internal section reference.
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Corrected a source file path name.
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I. Background
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Signals are a UNIX mechanism for handling asynchronous events such as
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pressing the terminal interrupt key (e.g. Ctrl-C), job control, memory
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access violations, I/O completion, and many others. Each signal is
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assigned a positive number. There are a number of mechanisms by which
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a process may cause a signal to be sent, including using the kill(2)
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system call or registering with certain device drivers.
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II. Problem Description
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Some mechanisms for causing a signal to be sent did not properly
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validate the signal number, in some cases allowing the kernel to
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attempt to deliver a negative or out-of-range signal number. Such
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errors were present in the ptrace(2) system call and the `spigot'
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video capture device driver.
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The error in ptrace(2) was introduced in FreeBSD version 4.2-RELEASE
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(4-STABLE dated Oct 26 04:34:41 2000 UTC).
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The `spigot' device driver (including the error) was introduced in
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FreeBSD 2.0.5. It has never been included in the kernel installed by
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default, nor in the GENERIC kernel configuration. Only systems with
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`device spigot' added to the kernel configuration are affected by this
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instance of the error.
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III. Impact
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In most cases, attempted delivery of a negative or out-of-range signal
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number will trigger an assertion failure and panic, thereby crashing
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the system. A malicious local user could use this vulnerability
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as a local denial-of-service attack.
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However, in FreeBSD 5.x, the assertion code is not present if the
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`INVARIANTS' kernel option is not used. In FreeBSD 5.0-RELEASE and
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5.1-RELEASE, `INVARIANTS' is not enabled by default. In this
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configuration, a malicious local user could use this vulnerability
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to modify kernel memory, potentially leading to complete system
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compromise. (FreeBSD 4.x is not vulnerable in this way.)
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IV. Workaround
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There is no workaround for the local denial-of-service attack.
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The more severe impact, present only in FreeBSD 5.x systems, can be
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avoided by uncommenting or adding the `INVARIANTS' line to your kernel
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configuration:
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options INVARIANTS #Enable calls of extra sanity checking
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Recompile your kernel as described in
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<URL:http://www.freebsd.org/handbook/kernelconfig.html>
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and reboot the system.
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NOTE WELL: This workaround is only for FreeBSD 5.x systems. This
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workaround does not eliminate the possibility of a local
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denial-of-service attack.
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V. Solution
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1) Upgrade your vulnerable system to 4.8-STABLE, or to any of the
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RELENG_4_8 (4.8-RELEASE-p2), RELENG_4_7 (4.7-RELEASE-p12), or
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RELENG_5_1 (5.1-RELEASE-p1) security branches dated after the
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respective correction dates.
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2) To patch your present system:
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a) Download the relevant patch from the location below, and verify the
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detached PGP signature using your PGP utility.
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[FreeBSD 5.1-RELEASE]
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# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-03:09/signal51.patch
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# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-03:09/signal51.patch.asc
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[FreeBSD 5.0-RELEASE]
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# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-03:09/signal50.patch
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# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-03:09/signal50.patch.asc
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[FreeBSD 4.8-RELEASE, 4.8-STABLE, 4.7-STABLE dated Jan 2 20:39:13 2003 UTC
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or later]
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# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-03:09/signal4s.patch
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# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-03:09/signal4s.patch.asc
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[FreeBSD 4.3-RELEASE through 4.7-RELEASE, 4.7-STABLE dated before
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Jan 2 20:39:13 2003 UTC]
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# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-03:09/signal47.patch
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# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-03:09/signal47.patch.asc
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b) Apply the patch.
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# cd /usr/src
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# patch < /path/to/patch
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c) Recompile your kernel as described in
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<URL:http://www.freebsd.org/handbook/kernelconfig.html>
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and reboot the system.
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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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Branch Revision
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Path
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- -------------------------------------------------------------------------
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src/sys/UPDATING
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RELENG_5_1 1.251.2.2
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RELENG_5_0 1.229.2.15
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RELENG_4_8 1.73.2.80.2.4
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RELENG_4_7 1.73.2.74.2.15
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RELENG_4_6 1.73.2.68.2.43
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RELENG_4_5 1.73.2.50.2.45
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RELENG_4_4 1.73.2.43.2.46
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RELENG_4_3 1.73.2.28.2.33
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src/sys/conf/newvers.sh
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RELENG_5_1 1.50.2.3
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RELENG_5_0 1.48.2.10
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RELENG_4_8 1.44.2.29.2.3
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RELENG_4_7 1.44.2.26.2.14
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RELENG_4_6 1.44.2.23.2.32
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RELENG_4_5 1.44.2.20.2.29
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RELENG_4_4 1.44.2.17.2.37
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RELENG_4_3 1.44.2.14.2.23
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src/sys/i386/isa/spigot.c
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RELENG_4 1.44.2.1
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RELENG_5_1 1.58.2.1
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RELENG_5_0 1.55.2.1
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RELENG_4_8 1.44.14.1
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RELENG_4_7 1.44.12.1
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RELENG_4_6 1.44.10.1
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RELENG_4_5 1.44.8.1
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RELENG_4_4 1.44.6.1
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RELENG_4_3 1.44.4.1
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src/sys/kern/sys_process.c
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RELENG_4 1.51.2.7
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RELENG_5_1 1.108.2.1
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RELENG_5_0 1.104.2.1
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RELENG_4_8 1.51.2.6.2.1
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RELENG_4_7 1.51.2.4.2.2
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RELENG_4_6 1.51.2.3.4.2
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RELENG_4_5 1.51.2.3.2.2
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RELENG_4_4 1.51.2.1.4.3
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RELENG_4_3 1.51.2.1.2.3
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src/sys/kern/kern_sig.c
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RELENG_5_1 1.239.2.1
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RELENG_5_0 1.197.2.1
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- -------------------------------------------------------------------------
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-----BEGIN PGP SIGNATURE-----
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-----END PGP SIGNATURE-----
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