Re: [patch] MdePkg: check Length para before use in DevPathToTextUsbWWID

["Gao, Liming" <liming.gao@intel.com>]

Reviewed-by: Liming Gao <liming.gao@intel.com>

> -----Original Message-----
> From: Bi, Dandan
> Sent: Monday, November 19, 2018 10:09 AM
> To: edk2-devel@lists.01.org
> Cc: Kinney, Michael D <michael.d.kinney@intel.com>; Gao, Liming <liming.gao@intel.com>
> Subject: [patch] MdePkg: check Length para before use in DevPathToTextUsbWWID
> 
> REF: https://bugzilla.tianocore.org/show_bug.cgi?id=1336
> 
> In function DevPathToTextUsbWWID, the Length parameter is used
> without check. This patch is to add check before using it.
> 
> Cc: Michael D Kinney <michael.d.kinney@intel.com>
> Cc: Liming Gao <liming.gao@intel.com>
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Dandan Bi <dandan.bi@intel.com>
> ---
>  MdePkg/Library/UefiDevicePathLib/DevicePathToText.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/MdePkg/Library/UefiDevicePathLib/DevicePathToText.c b/MdePkg/Library/UefiDevicePathLib/DevicePathToText.c
> index 97d279eeb2..678f3d0a92 100644
> --- a/MdePkg/Library/UefiDevicePathLib/DevicePathToText.c
> +++ b/MdePkg/Library/UefiDevicePathLib/DevicePathToText.c
> @@ -970,11 +970,11 @@ DevPathToTextUsbWWID (
> 
>    UsbWWId = DevPath;
> 
>    SerialNumberStr = (CHAR16 *) ((UINT8 *) UsbWWId + sizeof (USB_WWID_DEVICE_PATH));
>    Length = (UINT16) ((DevicePathNodeLength ((EFI_DEVICE_PATH_PROTOCOL *) UsbWWId) - sizeof (USB_WWID_DEVICE_PATH)) /
> sizeof (CHAR16));
> -  if (SerialNumberStr [Length - 1] != 0) {
> +  if (Length >= 1 && SerialNumberStr [Length - 1] != 0) {
>      //
>      // In case no NULL terminator in SerialNumber, create a new one with NULL terminator
>      //
>      NewStr = AllocateCopyPool ((Length + 1) * sizeof (CHAR16), SerialNumberStr);
>      ASSERT (NewStr != NULL);
> --
> 2.18.0.windows.1