From 1696b221b15e439162cfccd6bd04132e425dd2ff Mon Sep 17 00:00:00 2001
From: "Bi, Dandan" <dandan.bi@intel.com>
Date: Tue, 29 Aug 2017 14:44:37 +0800
Subject: [PATCH] MdeModulePkg/UefiHiiLib: Fix incorrect check for string
 length

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=681

For string opcode,when checking the valid string length,
it should exclude the Null-terminated character.
And for string in NameValue storage, need to exclude
the varname and also need to convert the Config string
length to Unicode string length.

Cc: Eric Dong <eric.dong@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Dandan Bi <dandan.bi@intel.com>
Reviewed-by: Eric Dong <eric.dong@intel.com>
---
 MdeModulePkg/Library/UefiHiiLib/HiiLib.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/MdeModulePkg/Library/UefiHiiLib/HiiLib.c b/MdeModulePkg/Library/UefiHiiLib/HiiLib.c
index cd0cd35a0f..583b9e516c 100644
--- a/MdeModulePkg/Library/UefiHiiLib/HiiLib.c
+++ b/MdeModulePkg/Library/UefiHiiLib/HiiLib.c
@@ -1607,7 +1607,7 @@ ValidateQuestionFromVfr (
             break;
           }
           //
-          // Get Width by OneOf Flags
+          // Get the Max size of the string.
           //
           Width  = (UINT16) (IfrString->MaxSize * sizeof (UINT16));
           if (NameValueType) {
@@ -1621,6 +1621,10 @@ ValidateQuestionFromVfr (
               //
               break;
             }
+            //
+            // Skip the VarName.
+            //
+            StringPtr += StrLen (QuestionName);
 
             //
             // Skip the "=".
@@ -1629,8 +1633,13 @@ ValidateQuestionFromVfr (
             
             //
             // Check current string length is less than maxsize
+            // e.g Config String: "0041004200430044", Unicode String: "ABCD". Unicode String length = Config String length / 4.
+            // Config string format in UEFI spec.
+            // <NvConfig> ::= <Label>'='<String>
+            // <String> ::= [<Char>]+
+            // <Char> ::= <HexCh>4
             //
-            if (StrSize (StringPtr) > Width) {
+            if (StrLen (StringPtr) / 4 > IfrString->MaxSize) {
               return EFI_INVALID_PARAMETER;
             }
           } else {
@@ -1660,7 +1669,7 @@ ValidateQuestionFromVfr (
             //
             // Check current string length is less than maxsize
             //
-            if (StrSize ((CHAR16 *) (VarBuffer + Offset)) > Width) {
+            if (StrLen ((CHAR16 *) (VarBuffer + Offset)) > IfrString->MaxSize) {
               return EFI_INVALID_PARAMETER;
             }
           }
-- 
2.39.2