[cfe-commits] r44422 - /cfe/trunk/Lex/LiteralSupport.cpp

[Ted Kremenek]

Author: kremenek
Date: Wed Nov 28 18:54:29 2007
New Revision: 44422

URL: http://llvm.org/viewvc/llvm-project?rev=44422&view=rev
Log:
Removed potential buffer overrun (spotted by Neil Booth) when NumericLiteralParser
converts a parsed literal into an APFloat. We are still performing a copy of the
string, which hopefully will be removed eventually for performance reasons. This
version now is at least safe.

Changed rounding in APFloat construction in NumericLiteralParser from rmTowardsZero
to rmNearestTiesToEven.

Modified:
    cfe/trunk/Lex/LiteralSupport.cpp

Modified: cfe/trunk/Lex/LiteralSupport.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/Lex/LiteralSupport.cpp?rev=44422&r1=44421&r2=44422&view=diff

==============================================================================
--- cfe/trunk/Lex/LiteralSupport.cpp (original)
+++ cfe/trunk/Lex/LiteralSupport.cpp Wed Nov 28 18:54:29 2007
@@ -413,26 +413,21 @@
 GetFloatValue(const llvm::fltSemantics &Format, bool* isExact) {
   using llvm::APFloat;
   
-  char floatChars[256];
-  strncpy(floatChars, ThisTokBegin, ThisTokEnd-ThisTokBegin);
-  floatChars[ThisTokEnd-ThisTokBegin] = '\0';
-
-#if 1
+  llvm::SmallVector<char,256> floatChars;
+  for (unsigned i = 0, n = ThisTokEnd-ThisTokBegin; i != n; ++i)
+    floatChars.push_back(ThisTokBegin[i]);
+  
+  floatChars.push_back('\0');
+  
   APFloat V (Format, APFloat::fcZero, false);
-
   APFloat::opStatus status;
-  status = V.convertFromString(floatChars,APFloat::rmTowardZero);
+  
+  status = V.convertFromString(&floatChars[0],APFloat::rmNearestTiesToEven);
   
   if (isExact)
     *isExact = status == APFloat::opOK;
   
   return V;
-#else
-  // FIXME: this is horrible!
-  APFloat V(strtod(floatChars, 0));
-  V.convert(Format, APFloat::rmTowardZero);
-  return V;
-#endif
 }
 
 void NumericLiteralParser::Diag(SourceLocation Loc, unsigned DiagID,