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)
144 lines
5.7 KiB
Text
144 lines
5.7 KiB
Text
-----BEGIN PGP SIGNED MESSAGE-----
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Hash: SHA1
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=============================================================================
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FreeBSD-SA-09:09.pipe Security Advisory
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The FreeBSD Project
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Topic: Local information disclosure via direct pipe writes
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Category: core
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Module: kern
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Announced: 2009-06-10
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Credits: Pieter de Boer
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Affects: All supported versions of FreeBSD.
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Corrected: 2009-06-10 10:31:11 UTC (RELENG_7, 7.2-STABLE)
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2009-06-10 10:31:11 UTC (RELENG_7_2, 7.2-RELEASE-p1)
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2009-06-10 10:31:11 UTC (RELENG_7_1, 7.1-RELEASE-p6)
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2009-06-10 10:31:11 UTC (RELENG_6, 6.4-STABLE)
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2009-06-10 10:31:11 UTC (RELENG_6_4, 6.4-RELEASE-p5)
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2009-06-10 10:31:11 UTC (RELENG_6_3, 6.3-RELEASE-p11)
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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 <URL:http://security.FreeBSD.org/>.
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I. Background
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One of the most commonly used forms of interprocess communication on
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FreeBSD and other UNIX-like systems is the (anonymous) pipe. In this
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mechanism, a pair of file descriptors is created, and data written to
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one descriptor can be read from the other.
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FreeBSD's pipe implementation contains an optimization known as "direct
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writes". In this optimization, rather than copying data into kernel
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memory when the write(2) system call is invoked and then copying the
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data again when the read(2) system call is invoked, the FreeBSD kernel
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takes advantage of virtual memory mapping to allow the data to be copied
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directly between processes.
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II. Problem Description
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An integer overflow in computing the set of pages containing data to be
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copied can result in virtual-to-physical address lookups not being
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performed.
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III. Impact
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An unprivileged process can read pages of memory which belong to other
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processes or to the kernel. These may contain information which is
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sensitive in itself; or may contain passwords or cryptographic keys
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which can be indirectly exploited to gain sensitive information or
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access.
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IV. Workaround
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No workaround is available, but systems without untrusted local users
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are not vulnerable. System administrators are reminded that even if a
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system is not intended to have untrusted local users, it may be possible
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for an attacker to exploit some other vulnerability to obtain local user
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access to a system.
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V. Solution
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Perform one of the following:
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1) Upgrade your vulnerable system to 6-STABLE, or 7-STABLE, or to the
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RELENG_7_2, RELENG_7_1, RELENG_6_4, or RELENG_6_3 security branch
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dated after the correction date.
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2) To patch your present system:
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The following patches have been verified to apply to FreeBSD 6.3, 6.4,
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7.1, and 7.2 systems.
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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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# fetch http://security.FreeBSD.org/patches/SA-09:09/pipe.patch
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# fetch http://security.FreeBSD.org/patches/SA-09:09/pipe.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> and reboot the
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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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CVS:
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Branch Revision
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Path
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- -------------------------------------------------------------------------
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RELENG_6
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src/sys/kern/sys_pipe.c 1.184.2.5
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RELENG_6_4
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src/UPDATING 1.416.2.40.2.9
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src/sys/conf/newvers.sh 1.69.2.18.2.11
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src/sys/kern/sys_pipe.c 1.184.2.4.2.2
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RELENG_6_3
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src/UPDATING 1.416.2.37.2.16
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src/sys/conf/newvers.sh 1.69.2.15.2.15
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src/sys/kern/sys_pipe.c 1.184.2.2.6.2
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RELENG_7
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src/sys/kern/sys_pipe.c 1.191.2.5
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RELENG_7_2
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src/UPDATING 1.507.2.23.2.4
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src/sys/conf/newvers.sh 1.72.2.11.2.5
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src/sys/kern/sys_pipe.c 1.191.2.3.4.2
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RELENG_7_1
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src/UPDATING 1.507.2.13.2.9
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src/sys/conf/newvers.sh 1.72.2.9.2.10
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src/sys/kern/sys_pipe.c 1.191.2.3.2.2
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- -------------------------------------------------------------------------
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Subversion:
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Branch/path Revision
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- -------------------------------------------------------------------------
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stable/6/ r193893
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releng/6.4/ r193893
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releng/6.3/ r193893
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stable/7/ r193893
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releng/7.2/ r193893
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releng/7.1/ r193893
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- -------------------------------------------------------------------------
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VII. References
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The latest revision of this advisory is available at
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http://security.FreeBSD.org/advisories/FreeBSD-SA-09:09.pipe.asc
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