Bug 1824803 (CVE-2020-11669)

Summary: CVE-2020-11669 kernel: powerpc: guest can cause DoS on POWER9 KVM hosts
Product: [Other] Security Response Reporter: Guilherme de Almeida Suckevicz <gsuckevi>
Component: vulnerabilityAssignee: Red Hat Product Security <security-response-team>
Status: CLOSED ERRATA QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: acaringi, airlied, bhu, blc, brdeoliv, bskeggs, dhoward, dvlasenk, esammons, fhrbata, hdegoede, hkrzesin, iboverma, ichavero, itamar, jarodwilson, jeremy, jforbes, jglisse, jlelli, john.j5live, jonathan, josef, jross, jshortt, jstancek, jwboyer, kernel-maint, kernel-mgr, lgoncalv, linville, masami256, mchehab, mcressma, mjg59, mlangsdo, nmurray, qzhao, rt-maint, rvrbovsk, sparks, steved, williams
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: kernel-5.2 Doc Type: If docs needed, set a value
Doc Text:
A flaw was found in the way Linux kernel running on the Power9 processor saves and restores its registers while going in and coming out of an idle state. The issue occurs when a guest kernel has Kernel Userspace Address Protection (KUAP) feature enabled. The idle_book3s function does not save and restore the Authority Mask Register (AMR), Authority Mask Override Register (AMOR) and User Authority Mask Override Register (UAMOR). A guest user may use this flaw to render the host system unusable resulting in DoS issue.
 Story Points: ---
Clone Of: Environment:
Last Closed: 2021-04-27 10:46:31 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: 1824804, 1829045    
Bug Blocks: 1824733    

Description Guilherme de Almeida Suckevicz 2020-04-16 13:21:39 UTC 
A flaw was found in the way Linux kernel running on the Power9 processor saves and restores its registers while going in and coming out of an idle state. The issue occurs when a guest kernel has Kernel Userspace Address Protection (KUAP) feature enabled. The idle_book3s function does not save and restore the Authority Mask Register (AMR), Authority Mask Override Register (AMOR) and User Authority Mask Override Register (UAMOR). A guest user may use this flaw to render the host system unusable resulting in DoS issue.


Upstream commit:
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  -> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=53a712bae5dd919521a58d7bad773b949358add0

Reference:
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  -> http://www.openwall.com/lists/oss-security/2020/04/15/1
Comment 1 Guilherme de Almeida Suckevicz 2020-04-16 13:23:02 UTC 
Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 1824804]
Comment 2 Justin M. Forbes 2020-04-16 13:39:09 UTC 
This was fixed for Fedora with the 5.0.17 stable kernel updates.
Comment 6 Prasad Pandit 2020-05-04 09:03:49 UTC 
Statement:

This issue does not affect the versions of the kernel package as shipped with the Red Hat Enterprise Linux 5, 6, 7, 8 and Red Hat Enterprise MRG 2.
Comment 9 errata-xmlrpc 2021-04-27 07:21:05 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7

Via RHSA-2021:1379 https://access.redhat.com/errata/RHSA-2021:1379
Comment 10 Product Security DevOps Team 2021-04-27 10:46:31 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-2020-11669