Bug 2019163 (CVE-2021-43057)

Summary:	CVE-2021-43057 kernel: use-after-free in the SELinux handler for PTRACE_TRACEME
Product:	[Other] Security Response	Reporter:	Guilherme de Almeida Suckevicz <gsuckevi>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED NOTABUG	QA Contact:
Severity:	high	Docs Contact:
Priority:	high
Version:	unspecified	CC:	acaringi, adscvr, airlied, alciregi, bdettelb, bhu, blc, brdeoliv, bskeggs, chwhite, crwood, dhoward, dvlasenk, fhrbata, fpacheco, hdegoede, hkrzesin, jarod, jarodwilson, jburrell, jeremy, jforbes, jglisse, jlelli, jonathan, josef, jshortt, jstancek, jwboyer, kcarcia, kernel-maint, kernel-mgr, lgoncalv, linville, masami256, mchehab, mlangsdo, nmurray, ptalbert, qzhao, rvrbovsk, steved, vkumar, walters, williams
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	kernel 5.15 rc3	Doc Type:	If docs needed, set a value
Doc Text:	A use-after-free read flaw was found in selinux_ptrace_traceme in security/selinux/hooks.c in SELinux handler for PTRACE_TRACEME in the Linux kernel. In this flaw, an attempt to access the subjective credentials of another task may cause memory corruption by a user with local access and escalate privileges.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2022-05-17 11:45:18 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:	2008145, 2019164, 2020966, 2021045
Bug Blocks:	2019165

Description Guilherme de Almeida Suckevicz 2021-11-01 17:58:02 UTC

An issue was discovered in the Linux kernel before 5.14.8. A use-after-free in selinux_ptrace_traceme (aka the SELinux handler for PTRACE_TRACEME) could be used by local attackers to cause memory corruption and escalate privileges. This occurs because of an attempt to access the subjective credentials of another task.

Reference:
https://bugs.chromium.org/p/project-zero/issues/detail?id=2229

Upstream patch:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a3727a8bac0a9e77c70820655fd8715523ba3db7

Comment 1 Guilherme de Almeida Suckevicz 2021-11-01 17:58:46 UTC

Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 2019164]

Comment 2 Justin M. Forbes 2021-11-02 20:51:22 UTC

This was fixed for Fedora with the 5.14.8 stable kernel updates.

Comment 9 Product Security DevOps Team 2022-05-17 11:45:15 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-2021-43057