leak-detective: remove hdr from the allocation list during realloc()

If realloc moves an allocation, the original allocation gets freed. We
therefore must remove the hdr from the list, as it is invalid. We can add it
afterwards once it has been updated, allowing us to unlock the list during
reallocation.

src/libstrongswan/utils/leak_detective.c

@@ -186,6 +186,58 @@ static bool enable_thread(bool enable)
 	return before;
 }
 
+/**
+ * Add a header to the beginning of the list
+ */
+static void add_hdr(memory_header_t *hdr)
+{
+	lock->lock(lock);
+	hdr->next = first_header.next;
+	if (hdr->next)
+	{
+		hdr->next->previous = hdr;
+	}
+	hdr->previous = &first_header;
+	first_header.next = hdr;
+	lock->unlock(lock);
+}
+
+/**
+ * Remove a header from the list
+ */
+static void remove_hdr(memory_header_t *hdr)
+{
+	lock->lock(lock);
+	if (hdr->next)
+	{
+		hdr->next->previous = hdr->previous;
+	}
+	hdr->previous->next = hdr->next;
+	lock->unlock(lock);
+}
+
+/**
+ * Check if a header is in the list
+ */
+static bool has_hdr(memory_header_t *hdr)
+{
+	memory_header_t *current;
+	bool found = FALSE;
+
+	lock->lock(lock);
+	for (current = &first_header; current != NULL; current = current->next)
+	{
+		if (current == hdr)
+		{
+			found = TRUE;
+			break;
+		}
+	}
+	lock->unlock(lock);
+
+	return found;
+}
+
 #ifdef __APPLE__
 
 /**
@@ -713,16 +765,7 @@ HOOK(void*, malloc, size_t bytes)
 	hdr->bytes = bytes;
 	tail->magic = MEMORY_TAIL_MAGIC;
 
-	/* insert at the beginning of the list */
-	lock->lock(lock);
-	hdr->next = first_header.next;
-	if (hdr->next)
-	{
-		hdr->next->previous = hdr;
-	}
-	hdr->previous = &first_header;
-	first_header.next = hdr;
-	lock->unlock(lock);
+	add_hdr(hdr);
 
 	return hdr + 1;
 }
@@ -755,10 +798,10 @@ HOOK(void*, valloc, size_t size)
  */
 HOOK(void, free, void *ptr)
 {
-	memory_header_t *hdr, *current;
+	memory_header_t *hdr;
 	memory_tail_t *tail;
 	backtrace_t *backtrace;
-	bool found = FALSE, before;
+	bool before;
 
 	if (!enabled || thread_disabled->get(thread_disabled))
 	{
@@ -777,17 +820,7 @@ HOOK(void, free, void *ptr)
 	if (hdr->magic != MEMORY_HEADER_MAGIC ||
 		tail->magic != MEMORY_TAIL_MAGIC)
 	{
-		lock->lock(lock);
-		for (current = &first_header; current != NULL; current = current->next)
-		{
-			if (current == hdr)
-			{
-				found = TRUE;
-				break;
-			}
-		}
-		lock->unlock(lock);
-		if (found)
+		if (has_hdr(hdr))
 		{
 			/* memory was allocated by our hooks but is corrupted */
 			fprintf(stderr, "freeing corrupted memory (%p): "
@@ -805,14 +838,7 @@ HOOK(void, free, void *ptr)
 	}
 	else
 	{
-		/* remove item from list */
-		lock->lock(lock);
-		if (hdr->next)
-		{
-			hdr->next->previous = hdr->previous;
-		}
-		hdr->previous->next = hdr->next;
-		lock->unlock(lock);
+		remove_hdr(hdr);
 
 		hdr->backtrace->destroy(hdr->backtrace);
 
@@ -848,6 +874,8 @@ HOOK(void*, realloc, void *old, size_t bytes)
 	hdr = old - sizeof(memory_header_t);
 	tail = old + hdr->bytes;
 
+	remove_hdr(hdr);
+
 	if (hdr->magic != MEMORY_HEADER_MAGIC ||
 		tail->magic != MEMORY_TAIL_MAGIC)
 	{
@@ -875,14 +903,7 @@ HOOK(void*, realloc, void *old, size_t bytes)
 	hdr->backtrace = backtrace_create(2);
 	enable_thread(before);
 
-	/* update header of linked list neighbours */
-	lock->lock(lock);
-	if (hdr->next)
-	{
-		hdr->next->previous = hdr;
-	}
-	hdr->previous->next = hdr;
-	lock->unlock(lock);
+	add_hdr(hdr);
 
 	return hdr + 1;
 }