test: add regression test for missing init() in realloc()

test/realloc_init.c

@@ -0,0 +1,33 @@
+#include <pthread.h>
+#include <stdlib.h>
+
+static void *thread_func(void *arg) {
+    arg = realloc(arg, 1024);
+    if (!arg) {
+        exit(EXIT_FAILURE);
+    }
+
+    free(arg);
+
+    return NULL;
+}
+
+int main(void) {
+    void *mem = realloc(NULL, 12);
+    if (!mem) {
+        return EXIT_FAILURE;
+    }
+
+    pthread_t thread;
+    int r = pthread_create(&thread, NULL, thread_func, mem);
+    if (r != 0) {
+        return EXIT_FAILURE;
+    }
+
+    r = pthread_join(thread, NULL);
+    if (r != 0) {
+        return EXIT_FAILURE;
+    }
+
+    return EXIT_SUCCESS;
+}