From d48828dd80ef8419e8b1dab4178340e654322719 Mon Sep 17 00:00:00 2001
From: gingerBill <bill@gingerbill.org>
Date: Thu, 13 Oct 2022 12:45:17 +0100
Subject: [PATCH] Add overflow check when using a growing arena

---
 core/mem/virtual/arena.odin | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/core/mem/virtual/arena.odin b/core/mem/virtual/arena.odin
index 3cc4cdbd6..57dbc2168 100644
--- a/core/mem/virtual/arena.odin
+++ b/core/mem/virtual/arena.odin
@@ -1,6 +1,7 @@
 package mem_virtual
 
 import "core:mem"
+import "core:intrinsics"
 
 Arena_Kind :: enum uint {
 	Growing = 0, // chained memory blocks (singly linked list)
@@ -56,7 +57,7 @@ arena_alloc :: proc(arena: ^Arena, size: uint, alignment: uint, loc := #caller_l
 
 	switch arena.kind {
 	case .Growing:
-		if arena.curr_block == nil || arena.curr_block.used + size > arena.curr_block.reserved {
+		if arena.curr_block == nil || (intrinsics.overflow_add(arena.curr_block.used, size) or_else 0) > arena.curr_block.reserved {
 			size = mem.align_forward_uint(size, alignment)
 			if arena.minimum_block_size == 0 {
 				arena.minimum_block_size = DEFAULT_ARENA_GROWING_MINIMUM_BLOCK_SIZE