Bug 1905636 (CVE-2020-29569)

Summary: CVE-2020-29569 xen: Use after free triggered by block frontend in Linux blkback (XSA-350)
Product: [Other] Security Response Reporter: Guilherme de Almeida Suckevicz <gsuckevi>
Component: vulnerabilityAssignee: Red Hat Product Security <security-response-team>
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: jforbes, m.a.young, robinlee.sysu, security-response-team
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Fixed In Version: Doc Type: If docs needed, set a value
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Clone Of: Environment:
Last Closed: 2020-12-15 22:19:47 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:
Bug Depends On: 1908082    
Bug Blocks: 1903644    

Description Guilherme de Almeida Suckevicz 2020-12-08 18:00:05 UTC
The Linux kernel PV block backend expects the kernel thread handler
to reset ring->xenblkd to NULL when stopped. However, the handler may
not have time to run if the frontend quickly toggle between the states
connect and disconnect.

As a consequence, the block backend may re-use a pointer after it was

Comment 1 Guilherme de Almeida Suckevicz 2020-12-15 19:53:52 UTC
External References:


Comment 2 Guilherme de Almeida Suckevicz 2020-12-15 19:54:06 UTC
Created xen tracking bugs for this issue:

Affects: fedora-all [bug 1908082]

Comment 3 Product Security DevOps Team 2020-12-15 22:19:47 UTC
This CVE Bugzilla entry is for community support informational purposes only as it does not affect a package in a commercially supported Red Hat product. Refer to the dependent bugs for status of those individual community products.

Comment 4 Justin M. Forbes 2021-03-04 22:02:00 UTC
This was fixed for Fedora with the 5.10.4 stable kernel updates.