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Bug 1778191 (CVE-2019-19582)

Summary: CVE-2019-19582 xen: denial of service in find_next_bit() (XSA-307)
Product: [Other] Security Response Reporter: Dhananjay Arunesh <darunesh>
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, security-response-team, vkuznets, xen-maint
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
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Story Points: ---
Clone Of: Environment:
Last Closed: 2020-02-18 15:16:52 UTC Type: ---
Regression: --- Mount Type: ---
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Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On: 1782211    
Bug Blocks:    

Description Dhananjay Arunesh 2019-11-29 13:11:04 UTC 
An issue was discovered in Xen through 4.12.x allowing x86 guest OS users to cause a denial of service (infinite loop) because certain bit iteration is mishandled. In a number of places bitmaps are being used by the hypervisor to track certain state. Iteration over all bits involves functions which may misbehave in certain corner cases: On x86 accesses to bitmaps with a compile time known size of 64 may incur undefined behavior, which may in particular result in infinite loops. A malicious guest may cause a hypervisor crash or hang, resulting in a Denial of Service (DoS). All versions of Xen are vulnerable. x86 systems with 64 or more nodes are vulnerable (there might not be any such systems that Xen would run on). x86 systems with less than 64 nodes are not vulnerable.
Comment 1 Marian Rehak 2019-12-11 12:41:42 UTC 
Created xen tracking bugs for this issue:

Affects: fedora-all [bug 1782211]
Comment 2 Dhananjay Arunesh 2019-12-12 06:26:26 UTC 
External References:

https://xenbits.xen.org/xsa/advisory-307.html