FreeBSD Errata Notices
2019-Jan-09 19:40 UTC
[FreeBSD-Announce] FreeBSD Errata Notice FreeBSD-EN-19:05.kqueue
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============================================================================FreeBSD-EN-19:05.kqueue
Errata Notice
The FreeBSD Project
Topic: kqueue race condition and kernel panic
Category: core
Module: kqueue
Announced: 2019-01-09
Credits: Mark Johnston
Affects: FreeBSD 11.2
Corrected: 2019-11-24 17:11:47 UTC (stable/11, 11.2-STABLE)
2019-01-09 18:57:38 UTC (releng/11.2, 11.2-RELEASE-p8)
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
kevent(2) is a system call which provides a generic method of notifying the
caller when a caller-specified event happens or a condition holds. One use
for kevent(2) is to wait for a specified timeout to elapse.
II. Problem Description
The kevent(2) implementation in the kernel contains a race condition which
can be triggered when an event is added and fires shortly after. Most event
types are not affected, but timer events can trigger the race if the timeout
duration is very short.
III. Impact
The race condition can cause corruption of a queue structure, leading to
a kernel panic when it is later accessed. Applications using kevent(2) may
trigger the panic if their usage causes the race condition to occur.
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 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-19:05/kqueue.patch
# fetch https://security.FreeBSD.org/patches/EN-19:05/kqueue.patch.asc
# gpg --verify kqueue.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/ r340904
releng/11.2/ r342899
- -------------------------------------------------------------------------
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-19:05.kqueue.asc>
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Cy Schubert
2019-Jan-09 20:02 UTC
[FreeBSD-Announce] FreeBSD Errata Notice FreeBSD-EN-19:05.kqueue
In message <20190109194030.DFE3A8CC7 at freefall.freebsd.org>, FreeBSD Errata Noti ces writes:> -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA512 > > ============================================================================> FreeBSD-EN-19:05.kqueue Errata Notice > The FreeBSD Project > > Topic: kqueue race condition and kernel panic > > Category: core > Module: kqueue > Announced: 2019-01-09 > Credits: Mark Johnston > Affects: FreeBSD 11.2 > Corrected: 2019-11-24 17:11:47 UTC (stable/11, 11.2-STABLE)Should this be 2018 or is this yet in the future?> 2019-01-09 18:57:38 UTC (releng/11.2, 11.2-RELEASE-p8) >[...] -- Cheers, Cy Schubert <Cy.Schubert at cschubert.com> FreeBSD UNIX: <cy at FreeBSD.org> Web: http://www.FreeBSD.org The need of the many outweighs the greed of the few.
Shawn Webb
2019-Feb-05 19:54 UTC
[FreeBSD-Announce] FreeBSD Errata Notice FreeBSD-EN-19:05.kqueue
On Wed, Jan 09, 2019 at 07:40:30PM +0000, FreeBSD Errata Notices wrote:> -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA512 > > ============================================================================> FreeBSD-EN-19:05.kqueue Errata Notice > The FreeBSD Project > > Topic: kqueue race condition and kernel panic > > Category: core > Module: kqueue > Announced: 2019-01-09 > Credits: Mark Johnston > Affects: FreeBSD 11.2 > Corrected: 2019-11-24 17:11:47 UTC (stable/11, 11.2-STABLE)Corrected November of 2018 or 2019? ;) -- Shawn Webb Cofounder and Security Engineer HardenedBSD Tor-ified Signal: +1 443-546-8752 Tor+XMPP+OTR: lattera at is.a.hacker.sx GPG Key ID: 0x6A84658F52456EEE GPG Key Fingerprint: 2ABA B6BD EF6A F486 BE89 3D9E 6A84 658F 5245 6EEE -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 833 bytes Desc: not available URL: <http://lists.freebsd.org/pipermail/freebsd-stable/attachments/20190205/27202986/attachment.sig>