patches to improve resistance to fault injection

targets/stm32l432/src/device.c

@@ -304,6 +304,12 @@ void device_init()
 
     hw_init(LOW_FREQUENCY);
 
+#if BOOT_TO_DFU
+    flash_option_bytes_init(1);
+#else
+    flash_option_bytes_init(0);
+#endif
+
     if (! tsc_sensor_exists())
     {
         _NFC_status = nfc_init();
@@ -329,12 +335,6 @@ void device_init()
 
     device_migrate();
 
-#if BOOT_TO_DFU
-    flash_option_bytes_init(1);
-#else
-    flash_option_bytes_init(0);
-#endif
-
 
 }
 

targets/stm32l432/src/flash.c

@@ -70,7 +70,11 @@ void flash_option_bytes_init(int boot_from_dfu)
 
     flash_lock();
 
-    __enable_irq();
+
+    /* Perform option byte loading which triggers a device reset. */
+    FLASH->CR |= FLASH_CR_OBL_LAUNCH;
+
+    while (true);
 }
 
 void flash_erase_page(uint8_t page)