From da8ad9ce190fab2e5cad499a1fd33ce08bcd05fd Mon Sep 17 00:00:00 2001
From: Rikard Falkeborn <rikard.falkeborn@gmail.com>
Date: Sat, 12 Sep 2020 18:46:01 +0200
Subject: [PATCH 1/2] memleakOnRealloc: Don't warn if pointer is NULL in
 condition

---
 lib/checkmemoryleak.cpp | 5 +++++
 test/testmemleak.cpp    | 4 ++--
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/lib/checkmemoryleak.cpp b/lib/checkmemoryleak.cpp
index 43c0664e2..4bcbc6625 100644
--- a/lib/checkmemoryleak.cpp
+++ b/lib/checkmemoryleak.cpp
@@ -550,6 +550,11 @@ void CheckMemoryLeakInFunction::checkReallocUsage()
                     Token::findmatch(scope->bodyStart, "[{};] %varid% = *| %name% .| %name%| [;=]", tok, tok->varId()))
                     continue;
 
+                // Check if the argument is known to be null, which means it is not a memory leak
+                if (arg->hasKnownIntValue() && arg->getKnownIntValue() == 0) {
+                    continue;
+                }
+
                 const Token* tokEndRealloc = reallocTok->linkAt(1);
                 // Check that the allocation isn't followed immediately by an 'if (!var) { error(); }' that might handle failure
                 if (Token::simpleMatch(tokEndRealloc->next(), "; if (") &&
diff --git a/test/testmemleak.cpp b/test/testmemleak.cpp
index b70b35921..1b598ef84 100644
--- a/test/testmemleak.cpp
+++ b/test/testmemleak.cpp
@@ -201,7 +201,7 @@ private:
               "    free(a);\n"
               "}");
 
-        TODO_ASSERT_EQUALS("", "[test.cpp:4]: (error) Common realloc mistake: 'a' nulled but not freed upon failure\n", errout.str());
+        ASSERT_EQUALS("", errout.str());
     }
 
     void realloc4() {
@@ -296,7 +296,7 @@ private:
               "        return;\n"
               "    free(a);\n"
               "}");
-        TODO_ASSERT_EQUALS("", "[test.cpp:4]: (error) Common realloc mistake: 'a' nulled but not freed upon failure\n", errout.str());
+        ASSERT_EQUALS("", errout.str());
     }
 
     void realloc13() {

From 791051ced0b37198d8de51145239930bae087dff Mon Sep 17 00:00:00 2001
From: Rikard Falkeborn <rikard.falkeborn@gmail.com>
Date: Fri, 31 Jul 2020 01:44:33 +0200
Subject: [PATCH 2/2] Fix #9228 (FN common realloc mistake with assignment of
 NULL)

Do not match for assignments with NULL.
---
 lib/checkmemoryleak.cpp |  2 +-
 test/testmemleak.cpp    | 30 ++++++++++++++++++++++++++++++
 2 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/lib/checkmemoryleak.cpp b/lib/checkmemoryleak.cpp
index 4bcbc6625..c19c3e2e3 100644
--- a/lib/checkmemoryleak.cpp
+++ b/lib/checkmemoryleak.cpp
@@ -547,7 +547,7 @@ 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% = *| %name% .| %name%| [;=]", tok, tok->varId()))
+                    Token::findmatch(scope->bodyStart, "[{};] %varid% = *| %var% .| %var%| [;=]", tok, tok->varId()))
                     continue;
 
                 // Check if the argument is known to be null, which means it is not a memory leak
diff --git a/test/testmemleak.cpp b/test/testmemleak.cpp
index 1b598ef84..4d98b15c7 100644
--- a/test/testmemleak.cpp
+++ b/test/testmemleak.cpp
@@ -169,6 +169,7 @@ private:
         TEST_CASE(realloc21);
         TEST_CASE(realloc22);
         TEST_CASE(realloc23);
+        TEST_CASE(realloc24); // #9228
         TEST_CASE(reallocarray1);
     }
 
@@ -410,6 +411,35 @@ private:
         ASSERT_EQUALS("", errout.str());
     }
 
+    void realloc24() { // #9228
+        check("void f() {\n"
+              "void *a = NULL;\n"
+              "a = realloc(a, 20);\n"
+              "}");
+        ASSERT_EQUALS("", errout.str());
+
+        check("void f() {\n"
+              "void *a = NULL;\n"
+              "a = malloc(10);\n"
+              "a = realloc(a, 20);\n"
+              "}");
+        ASSERT_EQUALS("[test.cpp:4]: (error) Common realloc mistake: \'a\' nulled but not freed upon failure\n", errout.str());
+
+        check("void f() {\n"
+              "void *a = std::nullptr;\n"
+              "a = malloc(10);\n"
+              "a = realloc(a, 20);\n"
+              "}");
+        ASSERT_EQUALS("[test.cpp:4]: (error) Common realloc mistake: \'a\' nulled but not freed upon failure\n", errout.str());
+
+        check("void f(char *b) {\n"
+              "void *a = NULL;\n"
+              "a = b;\n"
+              "a = realloc(a, 20);\n"
+              "}");
+        ASSERT_EQUALS("", errout.str());
+    }
+
     void reallocarray1() {
         check("void foo()\n"
               "{\n"