Date: Wed, 19 Dec 2018 20:52:39 +0000 (UTC) From: FreeBSD Errata Notices <errata-notices@freebsd.org> To: FreeBSD Errata Notices <errata-notices@freebsd.org> Subject: [FreeBSD-Announce] FreeBSD Errata Notice FreeBSD-EN-18:16.ptrace Message-ID: <20181219205239.5C6D419B5A@freefall.freebsd.org>
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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 ============================================================================= FreeBSD-EN-18:16.ptrace Errata Notice The FreeBSD Project Topic: kernel panic upon ptrace attach to stopped process Category: core Module: kernel Announced: 2018-12-19 Credits: John Baldwin, Konstantin Belousov Affects: FreeBSD 11.2 Corrected: 2018-11-09 17:43:23 UTC (stable/11, 11.2-STABLE) 2018-12-19 17:52:56 UTC (releng/11.2, 11.2-RELEASE-p7) For general information regarding FreeBSD Errata Notices and Security Advisories, including descriptions of the fields above, security branches, and the following sections, please visit <URL:https://security.FreeBSD.org/>. I. Background ptrace(2) is a system call used by debuggers and related utilities to take control of a process and inspect its state. To use the interface, a debugger must first attach to a target process. Once attached, the ptrace interface allows the debugger to intercept events, such as signal delivery, involving the target process. II. Problem Description The ptrace(2) implementation in FreeBSD 11.2 contains a bug such that a ptrace attach operation will trigger a kernel panic if the target process is in a stopped state. III. Impact Users debugging a problem with, for example, gdb, may cause the system to crash. IV. Workaround No workaround is available. V. Solution Perform one of the following: 1) Upgrade your system to a supported FreeBSD stable or release / security branch (releng) dated after the correction date, and reboot. 2) To update your system via a binary patch: Systems running a RELEASE version of FreeBSD on the i386 or amd64 platforms can be updated via the freebsd-update(8) utility: # freebsd-update fetch # freebsd-update install # shutdown -r +30 "Rebooting for FreeBSD errata update" 3) To update your system via a source code patch: The following patches have been verified to apply to the applicable FreeBSD release branches. a) Download the relevant patch from the location below, and verify the detached PGP signature using your PGP utility. [FreeBSD 11.2] # fetch https://security.FreeBSD.org/patches/EN-18:16/ptrace.patch # fetch https://security.FreeBSD.org/patches/EN-18:16/ptrace.patch.asc # gpg --verify ptrace.patch.asc b) Apply the patch. Execute the following commands as root: # cd /usr/src # patch < /path/to/patch c) Recompile your kernel as described in <URL:https://www.FreeBSD.org/handbook/kernelconfig.html> and reboot the system. VI. Correction details The following list contains the correction revision numbers for each affected branch. Branch/path Revision - ------------------------------------------------------------------------- stable/11/ r340290 releng/11.2/ r342224 - ------------------------------------------------------------------------- To see which files were modified by a particular revision, run the following command, replacing NNNNNN with the revision number, on a machine with Subversion installed: # svn diff -cNNNNNN --summarize svn://svn.freebsd.org/base Or visit the following URL, replacing NNNNNN with the revision number: <URL:https://svnweb.freebsd.org/base?view=revision&revision=NNNNNN> VII. References The latest revision of this advisory is available at <URL:https://security.FreeBSD.org/advisories/FreeBSD-EN-18:16.ptrace.asc> -----BEGIN PGP SIGNATURE----- iQKTBAEBCgB9FiEE/A6HiuWv54gCjWNV05eS9J6n5cIFAlwanjhfFIAAAAAALgAo aXNzdWVyLWZwckBub3RhdGlvbnMub3BlbnBncC5maWZ0aGhvcnNlbWFuLm5ldEZD MEU4NzhBRTVBRkU3ODgwMjhENjM1NUQzOTc5MkY0OUVBN0U1QzIACgkQ05eS9J6n 5cKOqQ//fJgy4vjyoteYlSq6DagrgleiA9DkM13OsGxqGPOyA5+H+aI4ZtD3mqcK u9p1eP3AA3sF5RLMvOpAMvJPYv1XMmHLm/15vGhjiLT7xK82jzH9Ic72hBnv6xm6 lzp2L7dUKQaXwv6AUR9tF6MQXRBlC5FtI3Tf8ajUsNHCA+lMXx2pjYoG6/gWroXn ycotsBYRicW6n6fJ+tTv9eVEI237+l+KUzqNH26e9Q6wkWtv4UNB5/FAauN6zovF AJSLs9eTa7QlxsGbJwh/EYuSjw085n9jIFVeMQPN3kIvDHbk59mymSpE6W37QRj0 c1Kq/nBI4WARrWvRf5KdZYXVJ/iKU3ndulE2gfmetbmHzCM4c7FcQaPqLM5htvfz sUbu3o3Vq/0/XFj1nyxjX8YIxdveRaopi8rWASyq7JfsieUZt5RPSZM9QgbmoB45 9fLCFMdMT2kBAUknIxoxlMAOzZV9p0d41Vu6M83Km5TC5iGItpYusScPh6qmxxC9 WQwh6MzeabGEIFcxv6mCj4IcWGdDevcCIUW/mQBzPFJTdFQwq+A6HdHsNHJSQYZy okY/P/CzUjupMYMLdbLjsxx7256Tm4wC2PVtvsyVZY/82IT0HGBq7pAp38R+3ANQ FieQ+S0F0IKZlyNnGGghbH+YYIsehqC24eoymeUFZDias7vyq1A= =5T6c -----END PGP SIGNATURE-----
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