[PATCH] [analyzer] Fix a crash by division by zero

[Takeshi Yoshimura]

When I conducted static analysis without core checkers, clang encountered
a crash by division by zero. The cause of the division-by-zero is
that BasicValueFactory::evalAPSInt() blindly operates divisions with
*any* known values. It means the SVal builder operates divisions even if
RHS value is zero. My fix is simply adding a RHS check before performing
the division in BasicValueFactory::evalAPSInt().

http://reviews.llvm.org/D10145

Files:
  lib/StaticAnalyzer/Core/BasicValueFactory.cpp

Index: lib/StaticAnalyzer/Core/BasicValueFactory.cpp
===================================================================
--- lib/StaticAnalyzer/Core/BasicValueFactory.cpp
+++ lib/StaticAnalyzer/Core/BasicValueFactory.cpp
@@ -154,9 +154,13 @@
       return &getValue( V1 * V2 );
 
     case BO_Div:
+      if (V2 == 0) // Avoid division by zero
+        return nullptr;
       return &getValue( V1 / V2 );
 
     case BO_Rem:
+      if (V2 == 0) // Avoid division by zero
+        return nullptr;
       return &getValue( V1 % V2 );
 
     case BO_Add:

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