From e15d00b21e9bbc252e436c243710cb9712465814 Mon Sep 17 00:00:00 2001
From: Valery Mironov <32071355+MBkkt@users.noreply.github.com>
Date: Mon, 28 Nov 2022 08:38:19 +0100
Subject: [PATCH] compact_array: Fix ubsan error (#284)

Do not `memcpy` or `deallocate` if `old_capacity == 0`. `Array() == nullptr` in this case, so `memcpy` is UB.

Fixes #283 .
---
 src/s2/util/gtl/compact_array.h | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/s2/util/gtl/compact_array.h b/src/s2/util/gtl/compact_array.h
index cbc4fe9a..033db144 100644
--- a/src/s2/util/gtl/compact_array.h
+++ b/src/s2/util/gtl/compact_array.h
@@ -413,8 +413,10 @@ class compact_array_base {
     value_allocator_type allocator;
 
     T* new_ptr = allocator.allocate(capacity());
-    memcpy(new_ptr, Array(), old_capacity * sizeof(T));
-    allocator.deallocate(Array(), old_capacity);
+    if (old_capacity != 0) {
+      memcpy(new_ptr, Array(), old_capacity * sizeof(T));
+      allocator.deallocate(Array(), old_capacity);
+    }
 
     SetArray(new_ptr);
   }