Bug 1335889 (CVE-2016-4794)

Summary:	CVE-2016-4794 kernel: Use after free in array_map_alloc
Product:	[Other] Security Response	Reporter:	Adam Mariš <amaris>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED ERRATA	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	aquini, arm-mgr, bhu, carnil, dhoward, fhrbata, gansalmon, iboverma, itamar, jforbes, jkacur, joelsmith, jonathan, jross, jwboyer, kernel-maint, kernel-mgr, kstutsma, lgoncalv, madhu.chinakonda, matt, mchehab, mcressma, nmurray, plougher, pmatouse, rt-maint, rvrbovsk, slawomir, williams, wmealing
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:	Use after free vulnerability was found in percpu using previously allocated memory in bpf. First __alloc_percpu_gfp() is called, then the memory is freed with free_percpu() which triggers async pcpu_balance_work and then pcpu_extend_area_map could use a chunk after it has been freed.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2019-06-08 02:51:50 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:	1335890, 1344568, 1344569, 1344570, 1344571, 1344572, 1344573, 1344574, 1344575
Bug Blocks:	1336283

Description Adam Mariš 2016-05-13 13:27:43 UTC

Use after free vulnerability was found in percpu using previously allocated memory in bpf. First __alloc_percpu_gfp() is called, then the memory is freed with free_percpu() which triggers async pcpu_balance_work and then pcpu_extend_area_map is hitting use-after-free.

CVE request (contains reproducer):
http://seclists.org/oss-sec/2016/q2/332

1: percpu: fix synchronization between chunk->map_extend_work and chunk destruction
( https://www.mail-archive.com/netdev@vger.kernel.org/msg111820.html )

2: percpu: fix synchronization between synchronous map extension and chunk destruction
( https://www.mail-archive.com/netdev@vger.kernel.org/msg111747.html )

Comment 1 Adam Mariš 2016-05-13 13:28:34 UTC

Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 1335890]

Comment 8 Wade Mealing 2016-06-10 05:33:02 UTC

Statement:

This issue does not affect the Linux kernels as shipped with Red Hat Enterprise Linux 4, 5 and 6.

This issue affects the Linux kernels as shipped with Red Hat Enterprise Linux 7 and MRG-2 and may be addressed in a future update.

Comment 11 Adam Mariš 2016-06-14 11:15:43 UTC

Upstream patches:

https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=4f996e234dad488e5d9ba0858bc1bae12eff82c3

https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=6710e594f71ccaad8101bc64321152af7cd9ea28

Comment 12 errata-xmlrpc 2016-11-03 16:33:25 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7

Via RHSA-2016:2574 https://rhn.redhat.com/errata/RHSA-2016-2574.html

Comment 13 errata-xmlrpc 2016-11-03 19:51:31 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7

Via RHSA-2016:2584 https://rhn.redhat.com/errata/RHSA-2016-2584.html

Comment 14 errata-xmlrpc 2016-11-03 21:35:10 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7

Via RHSA-2016:2574 https://rhn.redhat.com/errata/RHSA-2016-2574.html

Comment 15 errata-xmlrpc 2016-11-03 21:50:31 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7

Via RHSA-2016:2584 https://rhn.redhat.com/errata/RHSA-2016-2584.html