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)
156 lines
6 KiB
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156 lines
6 KiB
Text
-----BEGIN PGP SIGNED MESSAGE-----
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Hash: SHA1
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=============================================================================
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FreeBSD-SA-10:07.mbuf Security Advisory
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The FreeBSD Project
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Topic: Lost mbuf flag resulting in data corruption
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Category: core
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Module: kern
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Announced: 2010-07-13
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Credits: Ming Fu
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Affects: FreeBSD 7.x and later.
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Corrected: 2010-07-13 02:45:17 UTC (RELENG_8, 8.1-PRERELEASE)
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2010-07-13 02:45:17 UTC (RELENG_8_1, 8.1-RELEASE)
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2010-07-13 02:45:17 UTC (RELENG_8_0, 8.0-RELEASE-p4)
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2010-07-13 02:45:17 UTC (RELENG_7, 7.3-STABLE)
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2010-07-13 02:45:17 UTC (RELENG_7_3, 7.3-RELEASE-p2)
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2010-07-13 02:45:17 UTC (RELENG_7_1, 7.1-RELEASE-p13)
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CVE Name: CVE-2010-2693
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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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An mbuf is a basic unit of memory management in the FreeBSD kernel
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inter-process communication and networking subsystem. Network packets
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and socket buffers are dependent on mbufs for their storage.
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Data can be embedded directly in mbufs, or mbufs can instead reference
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external buffers. The sendfile(2) system call uses external mbuf storage
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to directly map the contents of a file into a chain of mbufs for
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transmission purposes. The mbuf object supports a read-only flag that
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must be honored to prevent modification or writes to buffer data in
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cases like these.
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II. Problem Description
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The read-only flag is not correctly copied when a mbuf buffer reference
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is duplicated. When the sendfile(2) system call is used to transmit
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data over the loopback interface, this can result in the backing pages
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for the transmitted file being modified, causing data corruption.
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III. Impact
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This data corruption can be exploited by an local attacker to escalate
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their privilege by carefully controlling the corruption of system files.
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It should be noted that the attacker can corrupt any file they have read
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access to.
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NOTE: While systems without untrusted local users are not affected by
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the security aspects of this issue, the potential for data corruption
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implies that this should still be treated as a critical erratum.
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IV. Workaround
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No workaround is available.
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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 7-STABLE or 8-STABLE, or to the
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RELENG_8_1, RELENG_8_0, RELENG_7_3, or RELENG_7_1 security branch dated
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after the correction date.
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2) To update your vulnerable system via a source code patch:
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The following patches have been verified to apply to FreeBSD 7.1, 7.3,
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8.0 and 8.1 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-10:07/mbuf.patch
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# fetch http://security.FreeBSD.org/patches/SA-10:07/mbuf.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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3) To update your vulnerable system via a binary patch:
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Systems running 7.1-RELEASE, 7.3-RELEASE, or 8.0-RELEASE on the i386 or
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amd64 platforms can be updated via the freebsd-update(8) utility:
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# freebsd-update fetch
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# freebsd-update install
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Now 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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CVS:
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Branch Revision
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Path
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- -------------------------------------------------------------------------
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RELENG_7
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src/sys/kern/uipc_mbuf.c 1.174.2.4
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RELENG_7_3
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src/UPDATING 1.507.2.34.2.4
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src/sys/conf/newvers.sh 1.72.2.16.2.6
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src/sys/kern/uipc_mbuf.c 1.174.2.3.4.2
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RELENG_7_1
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src/UPDATING 1.507.2.13.2.16
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src/sys/conf/newvers.sh 1.72.2.9.2.17
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src/sys/kern/uipc_mbuf.c 1.174.2.2.2.2
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RELENG_8
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src/sys/kern/uipc_mbuf.c 1.185.2.3
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RELENG_8_1
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src/UPDATING 1.632.2.14.2.2
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src/sys/conf/newvers.sh 1.83.2.10.2.4
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src/sys/kern/uipc_mbuf.c 1.185.2.2.2.2
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RELENG_8_0
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src/UPDATING 1.632.2.7.2.7
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src/sys/conf/newvers.sh 1.83.2.6.2.7
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src/sys/kern/uipc_mbuf.c 1.185.2.1.2.2
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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/7/ r209964
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releng/7.3/ r209964
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releng/7.1/ r209964
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stable/8/ r209964
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releng/8.0/ r209964
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releng/8.1/ r209964
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- -------------------------------------------------------------------------
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VII. References
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http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2010-2693
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The latest revision of this advisory is available at
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http://security.FreeBSD.org/advisories/FreeBSD-SA-10:07.mbuf.asc
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=Reds
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-----END PGP SIGNATURE-----
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