Bug 1757321 (CVE-2019-16413)

Summary:	CVE-2019-16413 kernel: i_size_read() infinite loop leads to denial of service
Product:	[Other] Security Response	Reporter:	msiddiqu
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED WONTFIX	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	acaringi, airlied, bdettelb, bhu, blc, brdeoliv, bskeggs, dhoward, dominik.mierzejewski, 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, nmurray, plougher, rt-maint, rvrbovsk, steved, williams
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 implementation of the 9p filesystem in the Linux kernel. The 9p filesystem does not protect i_size_write() properly, which causes an i_size_read() infinite loop. An attacker, able to mount a specially crafted filesystem, could cause a denial of service on SMP systems.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2020-03-17 10:31:43 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:
Bug Blocks:	1757323

Description msiddiqu 2019-10-01 08:38:50 UTC

An issue was discovered in the Linux kernel. The 9p filesystem did not protect i_size_write() properly, which causes an i_size_read() infinite loop and denial of service on SMP systems.

Upstream patch: 

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=5e3cc1ee1405a7eb3487ed24f786dec01b4cbe1f

References:  

https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.0.4
https://patchwork.kernel.org/patch/10753365/

Comment 3 Wade Mealing 2020-03-17 06:40:04 UTC

Mitigation:


As the 9p module will be auto-loaded when required, its use can be disabled  by preventing the module from loading with the following instructions:

# echo "install 9p /bin/true" >> /etc/modprobe.d/disable-9p.conf 
 
The system will need to be restarted if the 9p modules are loaded. In most circumstances, the 9p kernel modules will be unable to be unloaded while the filesystems are in use.

If the system requires this module to work correctly, this mitigation may not be suitable.

If you need further assistance, see KCS article https://access.redhat.com/solutions/41278 or contact Red Hat Global Support Services.

Comment 5 Product Security DevOps Team 2020-03-17 10:31:43 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-2019-16413