Bug 1997519 (CVE-2021-28697) - CVE-2021-28697 xen: malicious guest may be able to elevate its privileges leads to DoS
Summary: CVE-2021-28697 xen: malicious guest may be able to elevate its privileges lea...
Keywords:
Status: CLOSED UPSTREAM
Alias: CVE-2021-28697
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
URL:
Whiteboard:
Depends On: 1997520
Blocks: 1997570
TreeView+ depends on / blocked
 
Reported: 2021-08-25 12:42 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 15:35:31 UTC


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Description Dhananjay Arunesh 2021-08-25 12:42:16 UTC
Guest get permitted access to certain Xen-owned pages of memory.  The
majority of such pages remain allocated / associated with a guest for
its entire lifetime.  Grant table v2 status pages, however, get
de-allocated when a guest switched (back) from v2 to v1.  The freeing
of such pages requires that the hypervisor know where in the guest
these pages were mapped.  The hypervisor tracks only one use within
guest space, but racing requests from the guest to insert mappings of
these pages may result in any of them to become mapped in multiple
locations.  Upon switching back from v2 to v1, the guest would then
retain access to a page that was freed and perhaps re-used for other
purposes.

Comment 1 Dhananjay Arunesh 2021-08-25 12:42:47 UTC
Created xen tracking bugs for this issue:

Affects: fedora-all [bug 1997520]

Comment 2 Product Security DevOps Team 2021-08-26 15:35:31 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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