x86 pv: Race condition in typeref acquisition Xen...
Moderate severity
Unreviewed
Published
Jun 10, 2022
to the GitHub Advisory Database
•
Updated Jan 27, 2023
Description
Published by the National Vulnerability Database
Jun 9, 2022
Published to the GitHub Advisory Database
Jun 10, 2022
Last updated
Jan 27, 2023
x86 pv: Race condition in typeref acquisition Xen maintains a type reference count for pages, in addition to a regular reference count. This scheme is used to maintain invariants required for Xen's safety, e.g. PV guests may not have direct writeable access to pagetables; updates need auditing by Xen. Unfortunately, the logic for acquiring a type reference has a race condition, whereby a safely TLB flush is issued too early and creates a window where the guest can re-establish the read/write mapping before writeability is prohibited.
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