On 23.11.2021 22:07, Stefano Stabellini wrote: > From: Stefano Stabellini <stefano.stabellini@xxxxxxxxxx> > > 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@xxxxxxxxxxxxxxx > Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxx> Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
