From 99f71a9a2cdcbcf5f376dc482a833a1510fb41f2 Mon Sep 17 00:00:00 2001
From: Andreas Kling <awesomekling@gmail.com>
Date: Mon, 6 Jan 2020 13:05:40 +0100
Subject: [PATCH] Kernel: Randomize the stack canary on startup

---
 Kernel/StdLib.cpp | 3 ---
 Kernel/init.cpp   | 6 ++++++
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/Kernel/StdLib.cpp b/Kernel/StdLib.cpp
index 8407882089..bbc4a8b347 100644
--- a/Kernel/StdLib.cpp
+++ b/Kernel/StdLib.cpp
@@ -213,9 +213,6 @@ void free(void* p)
     return kfree(p);
 }
 
-extern u32 __stack_chk_guard;
-u32 __stack_chk_guard = (u32)0xc0000c13;
-
 [[noreturn]] void __stack_chk_fail()
 {
     ASSERT_NOT_REACHED();
diff --git a/Kernel/init.cpp b/Kernel/init.cpp
index b01d496abe..b7df3d8691 100644
--- a/Kernel/init.cpp
+++ b/Kernel/init.cpp
@@ -44,6 +44,7 @@
 #include <Kernel/Net/RTL8139NetworkAdapter.h>
 #include <Kernel/PCI/Access.h>
 #include <Kernel/PCI/Initializer.h>
+#include <Kernel/Random.h>
 #include <Kernel/TTY/PTYMultiplexer.h>
 #include <Kernel/TTY/VirtualConsole.h>
 #include <Kernel/VM/MemoryManager.h>
@@ -219,6 +220,9 @@ extern "C" int __cxa_atexit(void (*)(void*), void*, void*)
     return 0;
 }
 
+extern u32 __stack_chk_guard;
+u32 __stack_chk_guard;
+
 extern "C" [[noreturn]] void init(u32 physical_address_for_kernel_page_tables)
 {
     // this is only used one time, directly below here. we can't use this part
@@ -313,6 +317,8 @@ extern "C" [[noreturn]] void init(u32 physical_address_for_kernel_page_tables)
         kprintf("x86: No RDRAND support detected. Randomness will be shitty\n");
     }
 
+    __stack_chk_guard = get_good_random<u32>();
+
     RTC::initialize();
     PIC::initialize();
     gdt_init();