These structures are hardware interfaces, ensure the layout is
correct.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 hw/usb/dev-storage.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/hw/usb/dev-storage.c b/hw/usb/dev-storage.c
index 2d7306b0572..87c22476f6b 100644
--- a/hw/usb/dev-storage.c
+++ b/hw/usb/dev-storage.c
@@ -27,7 +27,7 @@
 #define MassStorageReset  0xff
 #define GetMaxLun         0xfe
 
-struct usb_msd_cbw {
+struct QEMU_PACKED usb_msd_cbw {
     uint32_t sig;
     uint32_t tag;
     uint32_t data_len;
@@ -636,6 +636,9 @@ static const TypeInfo usb_storage_dev_type_info = {
 
 static void usb_msd_register_types(void)
 {
+    qemu_build_assert(sizeof(struct usb_msd_cbw) == 31);
+    qemu_build_assert(sizeof(struct usb_msd_csw) == 13);
+
     type_register_static(&usb_storage_dev_type_info);
 }
 
-- 
2.45.2