From ae0dc227165b786ab0204874771ad97b847db37d Mon Sep 17 00:00:00 2001
From: Andreas Kling <awesomekling@gmail.com>
Date: Mon, 15 Apr 2019 23:48:31 +0200
Subject: [PATCH] Kernel: Make validate_read_from_kernel() return early for
 nullptr checks.

Null pointers are always invalid, so don't bother going through all the
various checks for them.
---
 Kernel/Process.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Kernel/Process.cpp b/Kernel/Process.cpp
index efadbc752d..4889335e9b 100644
--- a/Kernel/Process.cpp
+++ b/Kernel/Process.cpp
@@ -1371,6 +1371,8 @@ static KernelMemoryCheckResult check_kernel_memory_access(LinearAddress laddr, b
 
 bool Process::validate_read_from_kernel(LinearAddress laddr) const
 {
+    if (laddr.is_null())
+        return false;
     // We check extra carefully here since the first 4MB of the address space is identity-mapped.
     // This code allows access outside of the known used address ranges to get caught.
     auto kmc_result = check_kernel_memory_access(laddr, false);