CVE-2021-28699

inadequate grant-v2 status frames array bounds check 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.

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