diff --git a/drivers/usb/core/message.c b/drivers/usb/core/message.c
--- a/drivers/usb/core/message.c
+++ b/drivers/usb/core/message.c
@@ -1052,6 +1052,25 @@ int usb_string(struct usb_device *dev, int index, char *buf, size_t size)
 			UTF16_LITTLE_ENDIAN, buf, size);
 	buf[err] = 0;
 
+	/*
+	 * Some devices report string descriptors with a declared length
+	 * greater than the actual serial, leaving uninitialized firmware
+	 * memory (often including C0 control characters) appended to the
+	 * returned string. Truncate at the first control character so
+	 * callers get a clean, well-formed string.
+	 */
+	{
+		int i;
+		for (i = 0; i < err; i++) {
+			unsigned char c = buf[i];
+			if (c < 0x20 || c == 0x7f) {
+				buf[i] = 0;
+				err = i;
+				break;
+			}
+		}
+	}
+
 	if (tbuf[1] != USB_DT_STRING)
 		dev_dbg(&dev->dev,
 			"wrong descriptor type %02x for string %d (\"%s\")\n",