Bug 1771442 (CVE-2019-18422)

Summary: CVE-2019-18422 xen: ARM: Interrupts are unconditionally unmasked in exception handlers
Product: [Other] Security Response Reporter: Marian Rehak <mrehak>
Component: vulnerabilityAssignee: Red Hat Product Security <security-response-team>
Status: CLOSED NOTABUG QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: acaringi, ailan, bhu, brdeoliv, dhoward, drjones, dvlasenk, fhrbata, hkrzesin, imammedo, jforbes, jshortt, jstancek, knoel, m.a.young, mrezanin, nmurray, pbonzini, rkrcmar, robinlee.sysu, rvrbovsk, vkuznets, xen-maint
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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Last Closed: 2020-02-24 15:13:50 UTC Type: ---
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On: 1771443    
Bug Blocks: 1762982    

Description Marian Rehak 2019-11-12 11:40:38 UTC 
Interrupts are unconditionally unmasked in exception handlers. When an exception occurs on an ARM system which is handled without changing processor level, some interrupts are unconditionally enabled during exception entry. So exceptions which occur when interrupts are masked will effectively unmask the interrupts. A malicious guest might contrive to arrange for critical Xen code to run with interrupts erroneously enabled. This could lead to data corruption, denial of service, or possibly even privilege escalation. However a precise attack technique has not been identified.

Upstream issue and patch:

http://xenbits.xen.org/xsa/advisory-303.html
Comment 1 Marian Rehak 2019-11-12 11:40:49 UTC 
Created xen tracking bugs for this issue:

Affects: fedora-all [bug 1771443]