From 342245fa2121d6e6ec96e9f4a380811d5151a148 Mon Sep 17 00:00:00 2001
From: Ariel Abreu <facekapow@outlook.com>
Date: Thu, 3 Mar 2022 00:09:29 -0500
Subject: [PATCH] dtape getters: Return `NULL` if input is `NULL`

Found via UBSAN
---
 duct-tape/internal-include/darlingserver/duct-tape/task.h   | 3 +++
 duct-tape/internal-include/darlingserver/duct-tape/thread.h | 6 ++++++
 duct-tape/src/thread.c                                      | 2 +-
 3 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/duct-tape/internal-include/darlingserver/duct-tape/task.h b/duct-tape/internal-include/darlingserver/duct-tape/task.h
index 4c1f342..6eda66b 100644
--- a/duct-tape/internal-include/darlingserver/duct-tape/task.h
+++ b/duct-tape/internal-include/darlingserver/duct-tape/task.h
@@ -18,6 +18,9 @@ struct dtape_task {
 
 __attribute__((always_inline))
 static dtape_task_t* dtape_task_for_xnu_task(task_t xnu_task) {
+	if (!xnu_task) {
+		return NULL;
+	}
 	return (dtape_task_t*)((char*)xnu_task - offsetof(dtape_task_t, xnu_task));
 };
 
diff --git a/duct-tape/internal-include/darlingserver/duct-tape/thread.h b/duct-tape/internal-include/darlingserver/duct-tape/thread.h
index 23c61ee..f1f79cf 100644
--- a/duct-tape/internal-include/darlingserver/duct-tape/thread.h
+++ b/duct-tape/internal-include/darlingserver/duct-tape/thread.h
@@ -42,11 +42,17 @@ struct dtape_thread {
 
 __attribute__((always_inline))
 static dtape_thread_t* dtape_thread_for_xnu_thread(thread_t xnu_thread) {
+	if (!xnu_thread) {
+		return NULL;
+	}
 	return (dtape_thread_t*)((char*)xnu_thread - offsetof(dtape_thread_t, xnu_thread));
 };
 
 __attribute__((always_inline))
 static dtape_task_t* dtape_task_for_thread(dtape_thread_t* thread) {
+	if (!thread) {
+		return NULL;
+	}
 	return dtape_task_for_xnu_task(thread->xnu_thread.task);
 };
 
diff --git a/duct-tape/src/thread.c b/duct-tape/src/thread.c
index 07d19ad..5426e70 100644
--- a/duct-tape/src/thread.c
+++ b/duct-tape/src/thread.c
@@ -414,7 +414,7 @@ void dtape_thread_dying(dtape_thread_t* thread) {
 
 thread_t current_thread(void) {
 	dtape_thread_t* thread = dtape_hooks->current_thread();
-	return &thread->xnu_thread;
+	return thread ? &thread->xnu_thread : NULL;
 };
 
 void (thread_reference)(thread_t thread) {