Fix 10400: FP nullPointer - for loop condition (#3417)

lib/forwardanalyzer.cpp

@@ -411,6 +411,8 @@ struct ForwardTraversal {
                 if (updateRecursive(condTok) == Progress::Break)
                     return Break();
         }
+        if (!checkThen && !checkElse && !isDoWhile && analyzer->stopOnCondition(condTok) && stopUpdates())
+            return Break(Analyzer::Terminate::Conditional);
         // condition is false, we don't enter the loop
         if (checkElse)
             return Progress::Continue;

lib/programmemory.cpp

@@ -153,16 +153,18 @@ bool conditionIsTrue(const Token *condition, const ProgramMemory &programMemory)
     return !error && result == 1;
 }
 
+static bool frontIs(const std::vector<MathLib::bigint>& v, bool i)
+{
+    if (v.empty())
+        return false;
+    if (v.front())
+        return i;
+    return !i;
+}
+
 void programMemoryParseCondition(ProgramMemory& pm, const Token* tok, const Token* endTok, const Settings* settings, bool then)
 {
-    if (Token::Match(tok, "==|>=|<=|<|>|!=")) {
-        if (then && !Token::Match(tok, "==|>=|<=|<|>"))
-            return;
-        if (!then && !Token::Match(tok, "<|>|!="))
-            return;
-        ValueFlow::Value truevalue;
-        ValueFlow::Value falsevalue;
-        const Token* vartok = parseCompareInt(tok, truevalue, falsevalue, [&](const Token* t) -> std::vector<MathLib::bigint> {
+    auto eval = [&](const Token* t) -> std::vector<MathLib::bigint> {
         if (t->hasKnownIntValue())
             return {t->values().front().intvalue};
         MathLib::bigint result = 0;
@@ -171,7 +173,15 @@ void programMemoryParseCondition(ProgramMemory& pm, const Token* tok, const Toke
         if (!error)
             return {result};
         return std::vector<MathLib::bigint>{};
-        });
+    };
+    if (Token::Match(tok, "==|>=|<=|<|>|!=")) {
+        if (then && !Token::Match(tok, "==|>=|<=|<|>"))
+            return;
+        if (!then && !Token::Match(tok, "<|>|!="))
+            return;
+        ValueFlow::Value truevalue;
+        ValueFlow::Value falsevalue;
+        const Token* vartok = parseCompareInt(tok, truevalue, falsevalue, eval);
         if (!vartok)
             return;
         if (vartok->exprId() == 0)
@@ -194,6 +204,15 @@ void programMemoryParseCondition(ProgramMemory& pm, const Token* tok, const Toke
     } else if (!then && Token::simpleMatch(tok, "||")) {
         programMemoryParseCondition(pm, tok->astOperand1(), endTok, settings, then);
         programMemoryParseCondition(pm, tok->astOperand2(), endTok, settings, then);
+    } else if (Token::Match(tok, "&&|%oror%")) {
+        std::vector<MathLib::bigint> lhs = eval(tok->astOperand1());
+        std::vector<MathLib::bigint> rhs = eval(tok->astOperand2());
+        if (lhs.empty() || rhs.empty()) {
+            if (frontIs(lhs, !then))
+                programMemoryParseCondition(pm, tok->astOperand2(), endTok, settings, then);
+            if (frontIs(rhs, !then))
+                programMemoryParseCondition(pm, tok->astOperand1(), endTok, settings, then);
+        }
     } else if (tok->exprId() > 0) {
         if (then && !astIsPointer(tok) && !astIsBool(tok))
             return;

test/testnullpointer.cpp

@@ -118,6 +118,7 @@ private:
         TEST_CASE(nullpointer76); // #10408
         TEST_CASE(nullpointer77);
         TEST_CASE(nullpointer78); // #7802
+        TEST_CASE(nullpointer79); // #10400
         TEST_CASE(nullpointer_addressOf); // address of
         TEST_CASE(nullpointerSwitch); // #2626
         TEST_CASE(nullpointer_cast); // #4692
@@ -2418,6 +2419,18 @@ private:
         ASSERT_EQUALS("[test.cpp:6]: (error) Null pointer dereference: *pp\n", errout.str());
     }
 
+    void nullpointer79() // #10400
+    {
+        check("void resize(size_t nF, size_t nT) {\n"
+              "    double* pValues = nullptr;\n"
+              "    if (nF > 0 && nT > 0)\n"
+              "        pValues = new double[nF * nT];\n"
+              "    for (size_t cc = 0; cc < nF * nT; ++cc)\n"
+              "        pValues[cc] = 42;\n"
+              "}\n");
+        ASSERT_EQUALS("", errout.str());
+    }
+
     void nullpointer_addressOf() { // address of
         check("void f() {\n"
               "  struct X *x = 0;\n"

test/testvalueflow.cpp

@@ -3125,6 +3125,20 @@ private:
                "}";
         ASSERT_EQUALS(true, testValueOfX(code, 3U, 0));
         ASSERT_EQUALS(false, testValueOfX(code, 4U, 0));
+
+        code = "int g();\n"
+               "int f(bool i, bool j) {\n"
+               "    if (i && j) {}\n"
+               "    else {\n"
+               "        int x = 0;\n"
+               "        if (i)\n"
+               "            x = g();\n"
+               "        return x;\n"
+               "    }\n"
+               "    return 0;\n"
+               "}\n";
+        ASSERT_EQUALS(false, testValueOfXKnown(code, 8U, 0));
+        ASSERT_EQUALS(true, testValueOfX(code, 8U, 0));
     }
 
     void valueFlowForwardModifiedVariables() {