Bug 1701245 (CVE-2019-3901)

Summary:	CVE-2019-3901 kernel: perf_event_open() and execve() race in setuid programs allows a data leak
Product:	[Other] Security Response	Reporter:	Vladis Dronov <vdronov>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED ERRATA	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	airlied, bskeggs, hdegoede, ichavero, itamar, jarodwilson, jeremy, jforbes, jglisse, john.j5live, jonathan, josef, jwboyer, kernel-maint, labbott, linville, mchehab, mjg59, mmilgram, steved
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	If docs needed, set a value
Doc Text:	A race condition in perf_event_open() allows local attackers to leak sensitive data from setuid programs. As no relevant locks (in particular the cred_guard_mutex) are held during the ptrace_may_access() call, it is possible for the specified target task to perform an execve() syscall with setuid execution before perf_event_alloc() actually attaches to it, allowing an attacker to bypass the ptrace_may_access() check and the perf_event_exit_task(current) call that is performed in install_exec_creds() during privileged execve() calls.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2020-03-31 22:33:56 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:	1701620, 1701621, 1828291, 1828292, 1838773, 1838774
Bug Blocks:	1701243

Description Vladis Dronov 2019-04-18 13:37:54 UTC

A race condition in perf_event_open() allows local attackers to leak sensitive data from setuid programs. As no relevant locks (in particular the cred_guard_mutex) are held during the ptrace_may_access() call, it is possible for the specified target task to perform an execve() syscall with setuid execution before perf_event_alloc() actually attaches to it, allowing an attacker to bypass the ptrace_may_access() check and the perf_event_exit_task(current) call that is performed in install_exec_creds() during privileged execve() calls.

References:

https://bugs.chromium.org/p/project-zero/issues/detail?id=807

https://seclists.org/oss-sec/2019/q2/9

An upstream patch:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit?id=79c9ce57eb2d5f1497546a3946b4ae21b6fdc438

Comment 6 Vladis Dronov 2019-04-20 00:02:51 UTC

Notes:

Red Hat Enterprise Linux 6 does not have PERF_TYPE_BREAKPOINT implemented, so the attack surface is much more limited, and so severity of this security flaw is considered low for it.

Comment 7 errata-xmlrpc 2020-03-31 19:11:28 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7

Via RHSA-2020:1016 https://access.redhat.com/errata/RHSA-2020:1016

Comment 8 errata-xmlrpc 2020-03-31 19:20:30 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7

Via RHSA-2020:1070 https://access.redhat.com/errata/RHSA-2020:1070

Comment 9 Product Security DevOps Team 2020-03-31 22:33:56 UTC

This bug is now closed. Further updates for individual products will be reflected on the CVE page(s):

https://access.redhat.com/security/cve/cve-2019-3901

Comment 14 errata-xmlrpc 2020-06-11 02:09:59 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7.7 Extended Update Support

Via RHSA-2020:2522 https://access.redhat.com/errata/RHSA-2020:2522

Comment 16 errata-xmlrpc 2020-07-07 09:51:36 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7.6 Extended Update Support

Via RHSA-2020:2851 https://access.redhat.com/errata/RHSA-2020:2851