Re: [patch v2] BaseTools/VfrCompile: Avoid using uninitialized pointer

["Dong, Eric" <eric.dong@intel.com>]

Reviewed-by: Eric Dong <eric.dong@intel.com>

-----Original Message-----
From: Bi, Dandan 
Sent: Wednesday, May 9, 2018 1:02 PM
To: edk2-devel@lists.01.org
Cc: Dong, Eric <eric.dong@intel.com>; Gao, Liming <liming.gao@intel.com>; Gary Lin <glin@suse.com>
Subject: [patch v2] BaseTools/VfrCompile: Avoid using uninitialized pointer

V2:
Add function _INIT_OPHDR_COND () for variable initialization.
Make code logic more clean.

Previously _CLEAR_SAVED_OPHDR () is used for variable initialization, and we updated it to clean memory.
But _CLEAR_SAVED_OPHDR () is still called for variable initialization. This will cause uninitialized pointer will be checked to free and cause unexpected issue.

This patch is to add new function for variable initialization and keep _CLEAR_SAVED_OPHDR () to clean memory which is aligned with its function name.

Cc: Eric Dong <eric.dong@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Cc: Gary Lin <glin@suse.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Dandan Bi <dandan.bi@intel.com>
---
 BaseTools/Source/C/VfrCompile/VfrSyntax.g | 23 ++++++++++++++++++++---
 1 file changed, 20 insertions(+), 3 deletions(-)

diff --git a/BaseTools/Source/C/VfrCompile/VfrSyntax.g b/BaseTools/Source/C/VfrCompile/VfrSyntax.g
index 4b0a43606ea..84dd2c3ed3f 100644
--- a/BaseTools/Source/C/VfrCompile/VfrSyntax.g
+++ b/BaseTools/Source/C/VfrCompile/VfrSyntax.g
@@ -4084,11 +4084,19 @@ vfrStatementInvalidSaveRestoreDefaults :
 
 //
 // Root expression extension function called by other function.
 //
 vfrStatementExpression [UINT32 RootLevel, UINT32 ExpOpCount = 0] :
-  << if ($RootLevel == 0) {mCIfrOpHdrIndex ++; if (mCIfrOpHdrIndex >= MAX_IFR_EXPRESSION_DEPTH) _PCATCH (VFR_RETURN_INVALID_PARAMETER, 0, "The depth of expression exceeds the max supported level 8!"); _CLEAR_SAVED_OPHDR ();} >>
+                                                       <<
+                                                          if ($RootLevel == 0) {
+                                                            mCIfrOpHdrIndex ++;
+                                                            if (mCIfrOpHdrIndex >= MAX_IFR_EXPRESSION_DEPTH) {
+                                                              _PCATCH (VFR_RETURN_INVALID_PARAMETER, 0, "The depth of expression exceeds the max supported level 8!");
+                                                            }
+                                                            _INIT_OPHDR_COND ();
+                                                          }
+                                                       >>
   andTerm[$RootLevel, $ExpOpCount]
   (
     L:OR andTerm[$RootLevel, $ExpOpCount]              << $ExpOpCount++; CIfrOr OObj(L->getLine()); >>
   )*
                                                        << @@ -4988,10 +4996,11 @@ private:
   CIfrOpHeader *      mCIfrOpHdr[MAX_IFR_EXPRESSION_DEPTH];
   UINT32              mCIfrOpHdrLineNo[MAX_IFR_EXPRESSION_DEPTH];
   UINT8               mCIfrOpHdrIndex;
   VOID                _SAVE_OPHDR_COND (IN CIfrOpHeader &, IN BOOLEAN, UINT32 LineNo = 0);
   VOID                _CLEAR_SAVED_OPHDR (VOID);
+  VOID                _INIT_OPHDR_COND (VOID);
   BOOLEAN             _SET_SAVED_OPHDR_SCOPE (VOID);
 
 
   EFI_VARSTORE_INFO   mCurrQestVarInfo;
   EFI_GUID            *mOverrideClassGuid;
@@ -5077,20 +5086,28 @@ EfiVfrParser::_SAVE_OPHDR_COND (
     mCIfrOpHdr[mCIfrOpHdrIndex]       = new CIfrOpHeader(OpHdr);
     mCIfrOpHdrLineNo[mCIfrOpHdrIndex] = LineNo;
   }
 }
 
+VOID
+EfiVfrParser::_INIT_OPHDR_COND (
+  VOID
+  )
+{
+  mCIfrOpHdr[mCIfrOpHdrIndex]       = NULL;
+  mCIfrOpHdrLineNo[mCIfrOpHdrIndex] = 0; }
+
 VOID
 EfiVfrParser::_CLEAR_SAVED_OPHDR (
   VOID
   )
 {
   if (mCIfrOpHdr[mCIfrOpHdrIndex] != NULL) {
     delete mCIfrOpHdr[mCIfrOpHdrIndex];
-    mCIfrOpHdr[mCIfrOpHdrIndex]     = NULL;
+    mCIfrOpHdr[mCIfrOpHdrIndex] = NULL;
   }
-  mCIfrOpHdrLineNo[mCIfrOpHdrIndex] = 0;  }
 
 BOOLEAN
 EfiVfrParser::_SET_SAVED_OPHDR_SCOPE (
   VOID
--
2.14.3.windows.1