Fix #14718 memleakOnRealloc false positive (#8524)

Author: chrchr-github

lib/checkmemoryleak.cpp

@@ -477,8 +477,11 @@ void CheckMemoryLeakInFunction::checkReallocUsage()
 
                 // Check that another copy of the pointer wasn't saved earlier in the function
                 if (Token::findmatch(scope->bodyStart, "%name% = %varid% ;", tok, tok->varId()) ||
-                    Token::findmatch(scope->bodyStart, "[{};] %varid% = *| %var% .| %var%| [;=]", tok, tok->varId()))
+                    Token::findmatch(scope->bodyStart, "[{};] %varid% = *| %var%", tok, tok->varId()))
                     continue;
+                if (const Token* storeTok = Token::findmatch(scope->bodyStart, "[{};] %varid% = %name% (", tok, tok->varId()))
+                    if (storeTok->tokAt(3) != reallocTok && !mSettings->library.getAllocFuncInfo(storeTok->tokAt(3)))
+                        continue;
 
                 // Check if the argument is known to be null, which means it is not a memory leak
                 if (arg->hasKnownIntValue() && arg->getKnownIntValue() == 0) {

test/testmemleak.cpp

@@ -150,6 +150,7 @@ class TestMemleakInFunction : public TestFixture {
         TEST_CASE(realloc22);
         TEST_CASE(realloc23);
         TEST_CASE(realloc24); // #9228
+        TEST_CASE(realloc25);
     }
 
     void realloc1() {
@@ -418,6 +419,60 @@ class TestMemleakInFunction : public TestFixture {
               "}");
         ASSERT_EQUALS("", errout_str());
     }
+
+    void realloc25() {
+        check("struct T {\n"
+              "    char* ptr;\n"
+              "    size_t len;\n"
+              "};\n"
+              "struct S {\n"
+              "    struct T t;\n"
+              "};\n"
+              "void f(struct S* s, size_t len) {\n"
+              "    char* p = s->t.ptr;\n"
+              "    p = realloc(p, len);\n"
+              "    if (p) {\n"
+              "        s->t.ptr = p;\n"
+              "        s->t.len = len;\n"
+              "    }\n"
+              "}\n");
+        ASSERT_EQUALS("", errout_str());
+
+        check("struct T {\n"
+              "    char* ptr;\n"
+              "    size_t len;\n"
+              "};\n"
+              "struct S {\n"
+              "    struct T t[1];\n"
+              "};\n"
+              "void f(struct S* s, size_t len) {\n"
+              "    char* p = s->t[0].ptr;\n"
+              "    p = realloc(p, len);\n"
+              "    if (p) {\n"
+              "        s->t[0].ptr = p;\n"
+              "        s->t[0].len = len;\n"
+              "    }\n"
+              "}\n");
+        ASSERT_EQUALS("", errout_str());
+
+        check("struct T {\n" // #14718
+              "    char* ptr;\n"
+              "    size_t len;\n"
+              "};\n"
+              "struct S {\n"
+              "    struct T t;\n"
+              "};\n"
+              "char* get(struct T t) { return t.ptr; };\n"
+              "void f(struct S* s, size_t len) {\n"
+              "    char* p = get(s->t);\n"
+              "    p = realloc(p, len);\n"
+              "    if (p) {\n"
+              "        s->t.ptr = p;\n"
+              "        s->t.len = len;\n"
+              "    }\n"
+              "}\n");
+        ASSERT_EQUALS("", errout_str());
+    }
 };
 
 REGISTER_TEST(TestMemleakInFunction)