Bug 1901728 (CVE-2020-27784)

Summary:	CVE-2020-27784 kernel: deallocated instance in printer_ioctl() printer_ioctl() tries to access lock_printer_io of the printer_dev instance
Product:	[Other] Security Response	Reporter:	Dhananjay Arunesh <darunesh>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED NOTABUG	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	acaringi, adscvr, airlied, alciregi, bhu, blc, bmasney, brdeoliv, bskeggs, chwhite, crwood, ddepaula, debarbos, dhoward, dvlasenk, esammons, fhrbata, hdegoede, hkrzesin, hpa, iboverma, jarod, jarodwilson, jburrell, jfaracco, jferlan, jforbes, jglisse, jlelli, joe.lawrence, jonathan, josef, jross, jshortt, jstancek, jwboyer, jwyatt, kcarcia, kernel-maint, kernel-mgr, lgoncalv, linville, lleshchi, lzampier, masami256, mchehab, mcressma, mlangsdo, nmurray, ptalbert, qzhao, rt-maint, rvrbovsk, scweaver, security-response-team, steved, tyberry, vkumar, walters, williams, wmealing
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	Linux kernel 5.10	Doc Type:	If docs needed, set a value
Doc Text:	A flaw was found in the Linux kernel. This flaw allows a local user with permission to access a printer port and issue an ioctl, creating a use-after-free and corrupting memory or escalating privileges.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2021-11-08 01:25:00 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:	2122392
Bug Blocks:	1898663, 2122622

Description Dhananjay Arunesh 2020-11-25 21:18:09 UTC

A vulnerability was found in Kernel, where accessing a deallocated instance in printer_ioctl() printer_ioctl() tries to access of a printer_dev instance. However, Use-after-free arises because it had been freed by gprinter_free().

Upstream patch:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=e8d5f92b8d30bb4ade76494490c3c065e12411b1

Comment 9 Pedro Sampaio 2022-08-29 22:42:42 UTC

Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 2122392]

Comment 10 Justin M. Forbes 2022-08-31 16:19:27 UTC

This was fixed for Fedora with the 5.8.17 stable kernel updates.