Bug 1997522 (CVE-2021-28699)

Summary: CVE-2021-28699 xen: malicious guest kernel leads to DoS
Product: [Other] Security Response Reporter: Dhananjay Arunesh <darunesh>
Component: vulnerabilityAssignee: Red Hat Product Security <security-response-team>
Status: CLOSED UPSTREAM QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: jforbes, m.a.young
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: If docs needed, set a value
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2021-08-26 15:35:34 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: 1997523    
Bug Blocks: 1997570    

Description Dhananjay Arunesh 2021-08-25 12:45:54 UTC
The v2 grant table interface separates grant attributes from grant
status.  That is, when operating in this mode, a guest has two tables.
As a result, guests also need to be able to retrieve the addresses that
the new status tracking table can be accessed through.
For 32-bit guests on x86, translation of requests has to occur because
the interface structure layouts commonly differ between 32- and 64-bit.
The translation of the request to obtain the frame numbers of the
grant status table involves translating the resulting array of frame
numbers.  Since the space used to carry out the translation is limited,
the translation layer tells the core function the capacity of the array
within translation space.  Unfortunately the core function then only
enforces array bounds to be below 8 times the specified value, and would
write past the available space if enough frame numbers needed storing.

Comment 1 Dhananjay Arunesh 2021-08-25 12:46:17 UTC
Created xen tracking bugs for this issue:

Affects: fedora-all [bug 1997523]

Comment 2 Product Security DevOps Team 2021-08-26 15:35:34 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.