MdePkg: check Length para before use in DevPathToTextUsbWWID

[mirror_edk2.git] / MdePkg / Library / UefiDevicePathLib / DevicePathToText.c

diff --git a/MdePkg/Library/UefiDevicePathLib/DevicePathToText.c b/MdePkg/Library/UefiDevicePathLib/DevicePathToText.c
index 97d279eeb25b711090881b53e3939698492b2c69..678f3d0a922de61eb8a94c2bdd02b52668d5de9e 100644 (file)
--- a/MdePkg/Library/UefiDevicePathLib/DevicePathToText.c
+++ b/MdePkg/Library/UefiDevicePathLib/DevicePathToText.c
@@ -972,7 +972,7 @@ DevPathToTextUsbWWID (
 \r
   SerialNumberStr = (CHAR16 *) ((UINT8 *) UsbWWId + sizeof (USB_WWID_DEVICE_PATH));\r
   Length = (UINT16) ((DevicePathNodeLength ((EFI_DEVICE_PATH_PROTOCOL *) UsbWWId) - sizeof (USB_WWID_DEVICE_PATH)) / sizeof (CHAR16));\r
-  if (SerialNumberStr [Length - 1] != 0) {\r
+  if (Length >= 1 && SerialNumberStr [Length - 1] != 0) {\r
     //\r
     // In case no NULL terminator in SerialNumber, create a new one with NULL terminator\r
     //\r