126 lines
4.5 KiB
Text
126 lines
4.5 KiB
Text
-----BEGIN PGP SIGNED MESSAGE-----
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Hash: SHA512
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=============================================================================
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FreeBSD-EN-18:16.ptrace Errata Notice
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The FreeBSD Project
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Topic: kernel panic upon ptrace attach to stopped process
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Category: core
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Module: kernel
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Announced: 2018-12-19
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Credits: John Baldwin, Konstantin Belousov
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Affects: FreeBSD 11.2
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Corrected: 2018-11-09 17:43:23 UTC (stable/11, 11.2-STABLE)
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2018-12-19 17:52:56 UTC (releng/11.2, 11.2-RELEASE-p7)
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For general information regarding FreeBSD Errata Notices and Security
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Advisories, including descriptions of the fields above, security
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branches, and the following sections, please visit
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<URL:https://security.FreeBSD.org/>.
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I. Background
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ptrace(2) is a system call used by debuggers and related utilities
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to take control of a process and inspect its state. To use the
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interface, a debugger must first attach to a target process. Once
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attached, the ptrace interface allows the debugger to intercept events,
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such as signal delivery, involving the target process.
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II. Problem Description
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The ptrace(2) implementation in FreeBSD 11.2 contains a bug such that
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a ptrace attach operation will trigger a kernel panic if the target
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process is in a stopped state.
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III. Impact
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Users debugging a problem with, for example, gdb, may cause the system to
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crash.
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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 system to a supported FreeBSD stable or release / security
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branch (releng) dated after the correction date, and reboot.
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2) To update your system via a binary patch:
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Systems running a RELEASE version of FreeBSD on the i386 or amd64
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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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# shutdown -r +30 "Rebooting for FreeBSD errata update"
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3) To update your system via a source code patch:
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The following patches have been verified to apply to the applicable
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FreeBSD release branches.
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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 11.2]
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# fetch https://security.FreeBSD.org/patches/EN-18:16/ptrace.patch
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# fetch https://security.FreeBSD.org/patches/EN-18:16/ptrace.patch.asc
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# gpg --verify ptrace.patch.asc
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b) Apply the patch. Execute the following commands as root:
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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:https://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 correction revision numbers for each
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affected branch.
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Branch/path Revision
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- -------------------------------------------------------------------------
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stable/11/ r340290
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releng/11.2/ r342224
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- -------------------------------------------------------------------------
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To see which files were modified by a particular revision, run the
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following command, replacing NNNNNN with the revision number, on a
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machine with Subversion installed:
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# svn diff -cNNNNNN --summarize svn://svn.freebsd.org/base
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Or visit the following URL, replacing NNNNNN with the revision number:
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<URL:https://svnweb.freebsd.org/base?view=revision&revision=NNNNNN>
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VII. References
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The latest revision of this advisory is available at
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<URL:https://security.FreeBSD.org/advisories/FreeBSD-EN-18:16.ptrace.asc>
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