intel_iommu: allocate new key when creating new address space

We use the pointer to stack for key for new address space, this will break hash
table searching, fixing by g_malloc() a new key instead.

Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Acked-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

hw/i386/intel_iommu.c

@@ -2347,12 +2347,13 @@ VTDAddressSpace *vtd_find_add_as(IntelIOMMUState *s, PCIBus *bus, int devfn)
     char name[128];
 
     if (!vtd_bus) {
+        uintptr_t *new_key = g_malloc(sizeof(*new_key));
+        *new_key = (uintptr_t)bus;
         /* No corresponding free() */
         vtd_bus = g_malloc0(sizeof(VTDBus) + sizeof(VTDAddressSpace *) * \
                             X86_IOMMU_PCI_DEVFN_MAX);
         vtd_bus->bus = bus;
-        key = (uintptr_t)bus;
-        g_hash_table_insert(s->vtd_as_by_busptr, &key, vtd_bus);
+        g_hash_table_insert(s->vtd_as_by_busptr, new_key, vtd_bus);
     }
 
     vtd_dev_as = vtd_bus->dev_as[devfn];