From 04e40da1885f86a23c66dca0f034fe9cbb70665f Mon Sep 17 00:00:00 2001
From: Andreas Kling <kling@serenityos.org>
Date: Fri, 21 Feb 2020 16:03:03 +0100
Subject: [PATCH] Kernel: Fix crash when reading /proc/PID/vmobjects

InodeVMObjects can have nulled-out physical page slots. That just means
we haven't cached that page from disk right now.
---
 Kernel/VM/Region.cpp | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/Kernel/VM/Region.cpp b/Kernel/VM/Region.cpp
index 1db032ec74..2c02c045d3 100644
--- a/Kernel/VM/Region.cpp
+++ b/Kernel/VM/Region.cpp
@@ -235,7 +235,8 @@ NonnullOwnPtr<Region> Region::create_kernel_only(const Range& range, const Strin
 
 bool Region::should_cow(size_t page_index) const
 {
-    if (vmobject().physical_pages()[page_index]->is_shared_zero_page())
+    auto& slot = vmobject().physical_pages()[page_index];
+    if (slot && slot->is_shared_zero_page())
         return true;
     if (m_shared)
         return false;