Bug 1311558 (CVE-2016-2544)

Summary:	CVE-2016-2544 kernel: sound: use-after-free in snd_timer_stop
Product:	[Other] Security Response	Reporter:	Andrej Nemec <anemec>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED WONTFIX	QA Contact:
Severity:	low	Docs Contact:
Priority:	low
Version:	unspecified	CC:	agordeev, aquini, arm-mgr, bhu, dhoward, esammons, fhrbata, gansalmon, iboverma, itamar, jforbes, jkacur, joelsmith, jonathan, jross, jwboyer, kernel-maint, kernel-mgr, kstutsma, lgoncalv, lwang, madhu.chinakonda, matt, mchehab, mcressma, mguzik, nmurray, pholasek, plougher, rt-maint, rvrbovsk, vdronov, williams
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2016-03-04 20:30:12 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	1311573
Bug Blocks:	1311575

Description Andrej Nemec 2016-02-24 13:07:39 UTC

ALSA sequencer code has an open race between the timer setup ioctl and the close of the client. This was triggered by syzkaller fuzzer, and a use-after-free was caught there as a result.

Upstream patch:

http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=3567eb6af614dac436c4b16a8d426f9faed639b3

External references:

http://www.spinics.net/lists/alsa-devel/msg45102.html
https://lkml.org/lkml/2016/1/12/465

CVE-ID request and assignment:

http://seclists.org/oss-sec/2016/q1/133

http://seclists.org/oss-sec/2016/q1/410

Comment 1 Josh Boyer 2016-02-24 13:39:41 UTC

This was fixed in 4.3.6 with:

commit 5a5c8e77d66f24446b7e741ac2e3ae3127d9dd54
Author: Takashi Iwai <tiwai>
Date:   Tue Jan 12 15:36:27 2016 +0100

    ALSA: seq: Fix race at timer setup and close
    
    commit 3567eb6af614dac436c4b16a8d426f9faed639b3 upstream.
    

and in 4.4.2 with:

commit 0058ede73e1f441c003666f61671dfddfcbd5811
Author: Takashi Iwai <tiwai>
Date:   Tue Jan 12 15:36:27 2016 +0100

    ALSA: seq: Fix race at timer setup and close
    
    commit 3567eb6af614dac436c4b16a8d426f9faed639b3 upstream.

All Fedora branches are already on those or newer and should already contain the fix for this issue.

Comment 2 Andrej Nemec 2016-02-24 13:50:57 UTC

There were lots of CVE assignments for kernel vulnerabilities yesterday, just wanted to make sure Fedora has them. Feel free to close the tracker if they are all fixed. Thanks!

Comment 4 Vladis Dronov 2016-03-04 20:30:12 UTC

Statement:

This issue affects the Linux kernel packages as shipped with Red Hat Enterprise Linux 5, 6, 7 and MRG-2. This has been rated as having Low security impact and is not currently planned to be addressed in future updates. For additional information, refer to the Red Hat Enterprise Linux Life Cycle: https://access.redhat.com/support/policy/updates/errata/.