Bug 1781679 (CVE-2019-19447)

Summary:	CVE-2019-19447 kernel: mounting a crafted ext4 filesystem image, performing some operations, and unmounting can lead to a use-after-free in ext4_put_super in fs/ext4/super.c
Product:	[Other] Security Response	Reporter:	Marian Rehak <mrehak>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED ERRATA	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	acaringi, airlied, bdettelb, bhu, blc, brdeoliv, bskeggs, dhoward, dvlasenk, esammons, fhrbata, hdegoede, hkrzesin, iboverma, ichavero, itamar, jarodwilson, jeremy, jforbes, jglisse, jlelli, john.j5live, jonathan, josef, jross, jschorr, jshortt, jstancek, jwboyer, kernel-maint, kernel-mgr, labbott, lgoncalv, linville, masami256, matt, mchehab, mcressma, mjg59, mlangsdo, mmilgram, nmurray, qzhao, rt-maint, rvrbovsk, steved, williams, wmealing
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 flaw was found in the Linux kernel's ext4_unlink function. An attacker could corrupt memory or escalate privileges when deleting a file from a recently unmounted specially crafted ext4 filesystem, including local, USB, and iSCSI.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2020-05-12 16:32:05 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:	1781680, 1801046, 1801047, 1801048, 1801049, 1801050, 1888707, 1894479, 1894480, 1894481, 1894482
Bug Blocks:	1781681

Description Marian Rehak 2019-12-10 11:37:25 UTC

A user with permissions to mount and unmount a crafted ext4 file system, via any transport mechanism (local, USB, ISCSI) can lead to a use-after-free when attempting to delete a directory after the disk has been umounted.

This can lead to possible memory corruption and privilege escalation.

External Reference:

https://github.com/bobfuzzer/CVE/tree/master/CVE-2019-19447
https://bugzilla.kernel.org/show_bug.cgi?id=205433

Comment 1 Marian Rehak 2019-12-10 11:37:47 UTC

Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 1781680]

Comment 8 Eric Christensen 2020-02-13 16:36:10 UTC

Mitigation:

Ext4 filesytems are built into the kernel so it is not possible to prevent the kernel module from loading.  However, this flaw can be prevented by disallowing mounting of untrusted filesystems.

As mounting is a privileged operation, (except for device hotplug) removing the ability for mounting and unmounting will prevent this flaw from being exploited.

Comment 9 errata-xmlrpc 2020-05-12 15:12:28 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7

Via RHSA-2020:2104 https://access.redhat.com/errata/RHSA-2020:2104

Comment 10 Product Security DevOps Team 2020-05-12 16:32:05 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-2019-19447

Comment 11 Justin M. Forbes 2020-05-13 22:16:45 UTC

This was fixed for Fedora in the 5.4.4 stable kernel update.

Comment 12 errata-xmlrpc 2020-09-29 18:58:36 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7

Via RHSA-2020:4062 https://access.redhat.com/errata/RHSA-2020:4062

Comment 13 errata-xmlrpc 2020-09-29 20:52:28 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7

Via RHSA-2020:4060 https://access.redhat.com/errata/RHSA-2020:4060

Comment 30 errata-xmlrpc 2020-11-04 00:49:56 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2020:4431 https://access.redhat.com/errata/RHSA-2020:4431

Comment 31 errata-xmlrpc 2020-11-04 02:21:56 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2020:4609 https://access.redhat.com/errata/RHSA-2020:4609

Comment 35 errata-xmlrpc 2020-11-24 10:55:54 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7.7 Extended Update Support

Via RHSA-2020:5206 https://access.redhat.com/errata/RHSA-2020:5206

Comment 36 errata-xmlrpc 2020-12-15 08:55:00 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7.4 Advanced Update Support
  Red Hat Enterprise Linux 7.4 Update Services for SAP Solutions
  Red Hat Enterprise Linux 7.4 Telco Extended Update Support

Via RHSA-2020:5430 https://access.redhat.com/errata/RHSA-2020:5430

Comment 37 errata-xmlrpc 2020-12-22 09:32:46 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7.6 Extended Update Support

Via RHSA-2020:5656 https://access.redhat.com/errata/RHSA-2020:5656