Add test for UAF in multi-threaded context

Author: mrstanb

tests/regression/71-use_after_free/12-multi-threaded-uaf.c

@@ -0,0 +1,30 @@
+//PARAM: --set ana.activated[+] useAfterFree
+#include <stdlib.h>
+#include <stdio.h>
+#include <pthread.h>
+
+int* gptr;
+
+// Mutex to ensure we don't get race warnings, but the UAF warnings we actually care about
+pthread_mutex_t mtx = PTHREAD_MUTEX_INITIALIZER;
+
+void *t_other(void* p) {
+    pthread_mutex_lock(&mtx);
+    free(gptr); //WARN
+    pthread_mutex_unlock(&mtx);
+}
+
+int main() {
+    gptr = malloc(sizeof(int));
+    *gptr = 42;
+
+    pthread_t thread;
+    pthread_create(&thread, NULL, t_other, NULL);
+
+    pthread_mutex_lock(&mtx);
+    *gptr = 43; //WARN
+    free(gptr); //WARN
+    pthread_mutex_unlock(&mtx);
+
+    return 0;
+}