[clang] [analyzer] Adding taint analysis capability to unix.Malloc checker (PR #92420)

[Balazs Benics via cfe-commits]

================
@@ -48,6 +49,45 @@ void myfoo(int *p);
 void myfooint(int p);
 char *fooRetPtr(void);
 
+void t1(void) {
+  size_t size;
+  scanf("%zu", &size);
+  int *p = malloc(size); // expected-warning{{malloc is called with a tainted (potentially attacker controlled) value}}
+  free(p);
+}
+
+void t2(void) {
+  size_t size;
+  scanf("%zu", &size);
+  int *p = calloc(size,2); // expected-warning{{calloc is called with a tainted (potentially attacker controlled) value}}
+  free(p);
+}
+
+void t3(void) {
+  size_t size;
+  scanf("%zu", &size);
+  if (1024<size)
+    return;
+  int *p = malloc(size); // No warning expected as the the user input is bound
+  free(p);
+}
+
+void t4(void) {
+  size_t size;
+  int *p = malloc(sizeof(int)); 
+  scanf("%zu", &size);  
+  p = (int*) realloc((void*) p, size); // // expected-warning{{realloc is called with a tainted (potentially attacker controlled) value}}
----------------
steakhal wrote:

```suggestion
  p = (int*) realloc((void*) p, size); // expected-warning{{realloc is called with a tainted (potentially attacker controlled) value}}
```

https://github.com/llvm/llvm-project/pull/92420