memory leaks: Added checking of deallocate to see that the pointer isn't deallocated already

src/checkmemoryleak.cpp

@@ -1014,8 +1014,8 @@ void CheckMemoryLeakClass::simplifycode(Token *tok)
                 done = false;
             }
 
-            // Reduce "[;{}] alloc ; dealloc ;" => "[;{}]"
-            if (Token::Match(tok2, "[;{}] alloc ; dealloc ;"))
+            // Reduce "[;{}] alloc ; dealloc ; !!dealloc" => "[;{}]"
+            if (Token::Match(tok2, "[;{}] alloc ; dealloc ; !!dealloc"))
             {
                 erase(tok2, tok2->tokAt(5));
                 done = false;
@@ -1177,7 +1177,7 @@ void CheckMemoryLeakClass::CheckMemoryLeak_CheckScope(const Token *Tok1, const c
     }
 
     simplifycode(tok);
-    //tok->printOut( "simplifycode result" );
+    tok->printOut("simplifycode result");
 
     // If the variable is not allocated at all => no memory leak
     if (Token::findmatch(tok, "alloc") == 0)
@@ -1214,6 +1214,11 @@ void CheckMemoryLeakClass::CheckMemoryLeak_CheckScope(const Token *Tok1, const c
         MemoryLeak(result->tokAt(2), varname, alloctype);
     }
 
+    else if ((result = Token::findmatch(tok, "dealloc ; dealloc ;")) != NULL)
+    {
+        _errorLogger->reportErr(ErrorMessage::deallocDealloc(_tokenizer, result->tokAt(2)));
+    }
+
     else if (! Token::findmatch(tok, "dealloc") &&
              ! Token::findmatch(tok, "use") &&
              ! Token::findmatch(tok, "return use ;"))

src/errormessage.h

@@ -147,6 +147,15 @@ public:
         return true;
     }
 
+    static std::string deallocDealloc(const Tokenizer *tokenizer, const Token *Location)
+    {
+        return msg1(tokenizer, Location) + "Deallocating a deallocated pointer";
+    }
+    static bool deallocDealloc(const Settings &s)
+    {
+        return true;
+    }
+
     static std::string cstyleCast(const Tokenizer *tokenizer, const Token *Location)
     {
         return msg1(tokenizer, Location) + "C-style pointer casting";

test/testmemleak.cpp

@@ -165,6 +165,9 @@ private:
         TEST_CASE(dealloc_use_4);
         TEST_CASE(dealloc_use_5);
         TEST_CASE(dealloc_use_6);
+
+        // free a free'd pointer
+        TEST_CASE(freefree);
     }
 
 
@@ -1587,6 +1590,18 @@ private:
         ASSERT_EQUALS(std::string(""), errout.str());
     }
 
+
+    void freefree()
+    {
+        check("void foo()\n"
+              "{\n"
+              "    char *str = malloc(100);\n"
+              "    free(str);\n"
+              "    free(str);\n"
+              "}\n");
+        ASSERT_EQUALS(std::string("[test.cpp:5]: Deallocating a deallocated pointer\n"), errout.str());
+    }
+
 };
 
 REGISTER_TEST(TestMemleak)

tools/errmsg.cpp

@@ -72,6 +72,7 @@ int main()
     err.push_back(Message("mismatchAllocDealloc", Message::std, "Mismatching allocation and deallocation: %1", "varname"));
     err.push_back(Message("memleak", Message::std, "Memory leak: %1", "varname"));
     err.push_back(Message("resourceLeak", Message::std, "Resource leak: %1", "varname"));
+    err.push_back(Message("deallocDealloc", Message::std, "Deallocating a deallocated pointer"));
 
     // checkother.cpp..
     err.push_back(Message("cstyleCast", Message::style, "C-style pointer casting"));