From f081990717a821fb304afe0c96a879976faf1d99 Mon Sep 17 00:00:00 2001
From: Andreas Kling <awesomekling@gmail.com>
Date: Fri, 3 Jan 2020 12:48:28 +0100
Subject: [PATCH] Kernel: Use get_fast_random() for the random syscall stack
 offset

---
 Kernel/Syscall.cpp | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/Kernel/Syscall.cpp b/Kernel/Syscall.cpp
index 98cecb5343..e71281c446 100644
--- a/Kernel/Syscall.cpp
+++ b/Kernel/Syscall.cpp
@@ -1,6 +1,7 @@
 #include <Kernel/Arch/i386/CPU.h>
 #include <Kernel/Process.h>
 #include <Kernel/ProcessTracer.h>
+#include <Kernel/Random.h>
 #include <Kernel/Syscall.h>
 #include <Kernel/VM/MemoryManager.h>
 
@@ -94,7 +95,7 @@ void syscall_handler(RegisterDump regs)
 {
     // Apply a random offset in the range 0-255 to the stack pointer,
     // to make kernel stacks a bit less deterministic.
-    auto* ptr = (char*)__builtin_alloca(read_tsc() & 0xff);
+    auto* ptr = (char*)__builtin_alloca(get_fast_random<u8>());
     asm volatile(""
                  : "=m"(*ptr));