fixed signature verification for compressed binaries

Author: bakadave

cores/esp8266/Updater.cpp

@@ -284,8 +284,24 @@ bool UpdaterClass::end(bool evenIfRemaining){
     _hash->begin();
     for (uint32_t offset = 0; offset < binSize; offset += sizeof(buff)) {
       auto len = std::min(sizeof(buff), binSize - offset);
-      ESP.flashRead(_startAddress + offset, reinterpret_cast<uint32_t *>(&buff[0]), len);
-      _hash->add(buff, len);
+
+      if (len % 4 == 0) {
+            ESP.flashRead(_startAddress + offset, reinterpret_cast<uint32_t *>(&buff[0]), len);
+            _hash->add(buff, len);
+        }
+        else {
+            // Calculate padding needed to make len 4-byte aligned
+            uint32_t padLen = (len + 3) & ~3; // Rounds up to nearest multiple of 4
+            
+            // Temporary buffer to satisfy 4-byte alignment requirement
+            uint8_t tempBuff[padLen] = {0};
+            
+            // Read into the temporary buffer
+            ESP.flashRead(_startAddress + offset, reinterpret_cast<uint32_t *>(&tempBuff[0]), padLen); // Note: ESP.flashRead size parameter might be in 4-byte words, not bytes
+            
+            // Process only the relevant portion of the temp buffer
+            _hash->add(tempBuff, len); // Ensure only len bytes are processed, not including the padded bytes
+        }
     }
     _hash->end();