trace: fix str_dup mem leak

src/trace/trace.c

@@ -245,7 +245,7 @@ int re_trace_close(void)
 int re_trace_flush(void)
 {
 #ifdef RE_TRACE_ENABLED
-	int i, flush_count;
+	int flush_count;
 	struct trace_event *event_tmp;
 	struct trace_event *e;
 	char *json_arg;
@@ -255,11 +255,6 @@ int re_trace_flush(void)
 	if (!re_atomic_rlx(&trace.init))
 		return 0;
 
-	size_t json_arg_sz = 4096;
-	json_arg = mem_zalloc(json_arg_sz, NULL);
-	if (!json_arg)
-		return ENOMEM;
-
 	mtx_lock(&trace.lock);
 	event_tmp = trace.event_buffer_flush;
 	trace.event_buffer_flush = trace.event_buffer;
@@ -269,7 +264,18 @@ int re_trace_flush(void)
 	trace.event_count = 0;
 	mtx_unlock(&trace.lock);
 
-	for (i = 0; i < flush_count; i++)
+	size_t json_arg_sz = 4096;
+	json_arg = mem_zalloc(json_arg_sz, NULL);
+	if (!json_arg) {
+		for (int i = 0; i < flush_count; i++) {
+			e = &trace.event_buffer_flush[i];
+			if (e->arg_type == RE_TRACE_ARG_STRING_COPY)
+				mem_deref((void *)e->arg.a_str);
+		}
+		return ENOMEM;
+	}
+
+	for (int i = 0; i < flush_count; i++)
 	{
 		e = &trace.event_buffer_flush[i];