From 7757d874adc269dce5b6ee44792b6c5a3841ff58 Mon Sep 17 00:00:00 2001
From: Idan Horowitz <idan.horowitz@gmail.com>
Date: Sun, 26 Dec 2021 00:52:33 +0200
Subject: [PATCH] Kernel: Assert that a KmallocSubheap fits inside a page

Since we allocate the subheap in the first page of the given storage
let's assert that the subheap can actually fit in a single page, to
prevent the possible future headache of trying to debug the cause of
random kernel memory corruption :^)
---
 Kernel/Heap/kmalloc.cpp | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Kernel/Heap/kmalloc.cpp b/Kernel/Heap/kmalloc.cpp
index 7eb3bf0ddbd..613669d5b45 100644
--- a/Kernel/Heap/kmalloc.cpp
+++ b/Kernel/Heap/kmalloc.cpp
@@ -58,6 +58,7 @@ struct KmallocGlobalData {
     void add_subheap(u8* storage, size_t storage_size)
     {
         dbgln("Adding kmalloc subheap @ {} with size {}", storage, storage_size);
+        static_assert(sizeof(KmallocSubheap) <= PAGE_SIZE);
         auto* subheap = new (storage) KmallocSubheap(storage + PAGE_SIZE, storage_size - PAGE_SIZE);
         subheaps.append(*subheap);
     }