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Commit 36e8f60f authored by Stefano Stabellini's avatar Stefano Stabellini Committed by Boris Ostrovsky
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xen: detect uninitialized xenbus in xenbus_init



If the xenstore page hasn't been allocated properly, reading the value
of the related hvm_param (HVM_PARAM_STORE_PFN) won't actually return
error. Instead, it will succeed and return zero. Instead of attempting
to xen_remap a bad guest physical address, detect this condition and
return early.

Note that although a guest physical address of zero for
HVM_PARAM_STORE_PFN is theoretically possible, it is not a good choice
and zero has never been validly used in that capacity.

Also recognize all bits set as an invalid value.

For 32-bit Linux, any pfn above ULONG_MAX would get truncated. Pfns
above ULONG_MAX should never be passed by the Xen tools to HVM guests
anyway, so check for this condition and return early.

Cc: stable@vger.kernel.org
Signed-off-by: default avatarStefano Stabellini <stefano.stabellini@xilinx.com>
Reviewed-by: default avatarJuergen Gross <jgross@suse.com>
Reviewed-by: default avatarJan Beulich <jbeulich@suse.com>
Link: https://lore.kernel.org/r/20211123210748.1910236-1-sstabellini@kernel.org


Signed-off-by: default avatarBoris Ostrovsky <boris.ostrovsky@oracle.com>
parent de6da33e
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