From e8361ac175bc6c911cd03e74ecd31be40a8cae37 Mon Sep 17 00:00:00 2001
From: Jordan R Abrahams-Whitehead <ajordanr@google.org>
Date: Wed, 24 Nov 2021 15:31:40 +0900
Subject: [PATCH] v2: Crash when dereferencing nullopt for std::optional

Updated for r457743.
Original author hscham <hscham@chromium.org>.

TODO(b/192529039): this is a temporary patch to address security
concerns when migrating base:Optional and absl::optional to
std::optional. libcxx upstream is working on decoupling hardening and
debugging asserts and this patch should be replaced by the upstream
patch upon completion.
---
 libcxx/include/optional | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/libcxx/include/optional b/libcxx/include/optional
index 8dc1a136fdaf..1772d2810525 100644
--- a/libcxx/include/optional
+++ b/libcxx/include/optional
@@ -158,6 +158,8 @@ template<class T>
 
 */
 
+#include <stdio.h>
+
 #include <__assert> // all public C++ headers provide the assertion handler
 #include <__availability>
 #include <__concepts/invocable.h>
@@ -923,56 +925,86 @@ public:
     }
 
     _LIBCPP_INLINE_VISIBILITY
+    _LIBCPP_AVAILABILITY_THROW_BAD_OPTIONAL_ACCESS
     constexpr
     add_pointer_t<value_type const>
     operator->() const
     {
         _LIBCPP_ASSERT(this->has_value(), "optional operator-> called on a disengaged value");
+        if (!this->has_value()) {
+          fprintf(stderr, "optional operator-> called on a disengaged value\n");
+          __builtin_trap();
+        }
         return _VSTD::addressof(this->__get());
     }
 
     _LIBCPP_INLINE_VISIBILITY
+    _LIBCPP_AVAILABILITY_THROW_BAD_OPTIONAL_ACCESS
     constexpr
     add_pointer_t<value_type>
     operator->()
     {
         _LIBCPP_ASSERT(this->has_value(), "optional operator-> called on a disengaged value");
+        if (!this->has_value()) {
+          fprintf(stderr, "optional operator-> called on a disengaged value\n");
+          __builtin_trap();
+        }
         return _VSTD::addressof(this->__get());
     }
 
     _LIBCPP_INLINE_VISIBILITY
+    _LIBCPP_AVAILABILITY_THROW_BAD_OPTIONAL_ACCESS
     constexpr
     const value_type&
     operator*() const& noexcept
     {
         _LIBCPP_ASSERT(this->has_value(), "optional operator* called on a disengaged value");
+        if (!this->has_value()) {
+          fprintf(stderr, "optional operator* called on a disengaged value\n");
+          __builtin_trap();
+        }
         return this->__get();
     }
 
     _LIBCPP_INLINE_VISIBILITY
+    _LIBCPP_AVAILABILITY_THROW_BAD_OPTIONAL_ACCESS
     constexpr
     value_type&
     operator*() & noexcept
     {
         _LIBCPP_ASSERT(this->has_value(), "optional operator* called on a disengaged value");
+        if (!this->has_value()) {
+          fprintf(stderr, "optional operator* called on a disengaged value\n");
+          __builtin_trap();
+        }
         return this->__get();
     }
 
     _LIBCPP_INLINE_VISIBILITY
+    _LIBCPP_AVAILABILITY_THROW_BAD_OPTIONAL_ACCESS
     constexpr
     value_type&&
     operator*() && noexcept
     {
         _LIBCPP_ASSERT(this->has_value(), "optional operator* called on a disengaged value");
+        if (!this->has_value()) {
+          fprintf(stderr, "optional operator* called on a disengaged value\n");
+          __builtin_trap();
+        }
         return _VSTD::move(this->__get());
     }
 
     _LIBCPP_INLINE_VISIBILITY
+    _LIBCPP_AVAILABILITY_THROW_BAD_OPTIONAL_ACCESS
     constexpr
     const value_type&&
     operator*() const&& noexcept
     {
         _LIBCPP_ASSERT(this->has_value(), "optional operator* called on a disengaged value");
+        if (!this->has_value()) {
+          fprintf(stderr, "optional operator* called on a disengaged value\n");
+          __builtin_trap();
+        }
         return _VSTD::move(this->__get());
     }
 
-- 
2.35.1.1094.g7c7d902a7c-goog