Bug 1997522 (CVE-2021-28699) - CVE-2021-28699 xen: malicious guest kernel leads to DoS
Summary: CVE-2021-28699 xen: malicious guest kernel leads to DoS
Alias: CVE-2021-28699
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
Depends On: 1997523
Blocks: 1997570
TreeView+ depends on / blocked
Reported: 2021-08-25 12:45 UTC by Dhananjay Arunesh
Modified: 2021-08-26 15:35 UTC (History)
2 users (show)

Fixed In Version:
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Last Closed: 2021-08-26 15:35:34 UTC

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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.

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