ppc/pnv: fix check on return value of blk_getlength()

blk_getlength() returns an int64_t but the result is stored in a
uint32_t. Errors (negative values) won't be caught by the check in
pnv_pnor_realize() and blk_blockalign() will allocate a very large
buffer in such cases.

Fixes Coverity issue CID 1412226.
Signed-off-by: NCédric Le Goater <clg@kaod.org>
Message-Id: <20200107171809.15556-3-clg@kaod.org>
Reviewed-by: NGreg Kurz <groug@kaod.org>
Reviewed-by: NPhilippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: NDavid Gibson <david@gibson.dropbear.id.au>

hw/ppc/pnv_pnor.c

@@ -111,7 +111,7 @@ static void pnv_pnor_realize(DeviceState *dev, Error **errp)
 }
 
 static Property pnv_pnor_properties[] = {
-    DEFINE_PROP_UINT32("size", PnvPnor, size, 128 << 20),
+    DEFINE_PROP_INT64("size", PnvPnor, size, 128 << 20),
     DEFINE_PROP_DRIVE("drive", PnvPnor, blk),
     DEFINE_PROP_END_OF_LIST(),
 };

include/hw/ppc/pnv_pnor.h

@@ -23,7 +23,7 @@ typedef struct PnvPnor {
     BlockBackend   *blk;
 
     uint8_t        *storage;
-    uint32_t       size;
+    int64_t        size;
     MemoryRegion   mmio;
 } PnvPnor;