From 9f3f615e054663fd6e538fa2db86271b467a6bfd Mon Sep 17 00:00:00 2001
From: Liam <byteslice@airmail.cc>
Date: Fri, 14 Jul 2023 22:32:24 -0400
Subject: [PATCH] core: reduce TOCTTOU memory access

---
 src/core/debugger/gdbstub.cpp                   |  9 +++------
 src/core/hle/kernel/svc/svc_ipc.cpp             | 11 ++++-------
 src/core/hle/kernel/svc/svc_synchronization.cpp | 11 ++++-------
 3 files changed, 11 insertions(+), 20 deletions(-)

diff --git a/src/core/debugger/gdbstub.cpp b/src/core/debugger/gdbstub.cpp
index da6078372..0f839d5b4 100644
--- a/src/core/debugger/gdbstub.cpp
+++ b/src/core/debugger/gdbstub.cpp
@@ -261,10 +261,8 @@ void GDBStub::ExecuteCommand(std::string_view packet, std::vector<DebuggerAction
         const size_t addr{static_cast<size_t>(strtoll(command.data(), nullptr, 16))};
         const size_t size{static_cast<size_t>(strtoll(command.data() + sep, nullptr, 16))};
 
-        if (system.ApplicationMemory().IsValidVirtualAddressRange(addr, size)) {
-            std::vector<u8> mem(size);
-            system.ApplicationMemory().ReadBlock(addr, mem.data(), size);
-
+        std::vector<u8> mem(size);
+        if (system.ApplicationMemory().ReadBlock(addr, mem.data(), size)) {
             SendReply(Common::HexToString(mem));
         } else {
             SendReply(GDB_STUB_REPLY_ERR);
@@ -281,8 +279,7 @@ void GDBStub::ExecuteCommand(std::string_view packet, std::vector<DebuggerAction
         const auto mem_substr{std::string_view(command).substr(mem_sep)};
         const auto mem{Common::HexStringToVector(mem_substr, false)};
 
-        if (system.ApplicationMemory().IsValidVirtualAddressRange(addr, size)) {
-            system.ApplicationMemory().WriteBlock(addr, mem.data(), size);
+        if (system.ApplicationMemory().WriteBlock(addr, mem.data(), size)) {
             system.InvalidateCpuInstructionCacheRange(addr, size);
             SendReply(GDB_STUB_REPLY_OK);
         } else {
diff --git a/src/core/hle/kernel/svc/svc_ipc.cpp b/src/core/hle/kernel/svc/svc_ipc.cpp
index bb94f6934..373ae7c8d 100644
--- a/src/core/hle/kernel/svc/svc_ipc.cpp
+++ b/src/core/hle/kernel/svc/svc_ipc.cpp
@@ -8,6 +8,7 @@
 #include "core/hle/kernel/k_process.h"
 #include "core/hle/kernel/k_server_session.h"
 #include "core/hle/kernel/svc.h"
+#include "core/hle/kernel/svc_results.h"
 
 namespace Kernel::Svc {
 
@@ -49,14 +50,10 @@ Result ReplyAndReceive(Core::System& system, s32* out_index, uint64_t handles_ad
 
     // Copy user handles.
     if (num_handles > 0) {
-        // Ensure we can try to get the handles.
-        R_UNLESS(GetCurrentMemory(kernel).IsValidVirtualAddressRange(
-                     handles_addr, static_cast<u64>(sizeof(Handle) * num_handles)),
-                 ResultInvalidPointer);
-
         // Get the handles.
-        GetCurrentMemory(kernel).ReadBlock(handles_addr, handles.data(),
-                                           sizeof(Handle) * num_handles);
+        R_UNLESS(GetCurrentMemory(kernel).ReadBlock(handles_addr, handles.data(),
+                                                    sizeof(Handle) * num_handles),
+                 ResultInvalidPointer);
 
         // Convert the handles to objects.
         R_UNLESS(handle_table.GetMultipleObjects<KSynchronizationObject>(
diff --git a/src/core/hle/kernel/svc/svc_synchronization.cpp b/src/core/hle/kernel/svc/svc_synchronization.cpp
index f02d03f30..366e8ed4a 100644
--- a/src/core/hle/kernel/svc/svc_synchronization.cpp
+++ b/src/core/hle/kernel/svc/svc_synchronization.cpp
@@ -7,6 +7,7 @@
 #include "core/hle/kernel/k_process.h"
 #include "core/hle/kernel/k_readable_event.h"
 #include "core/hle/kernel/svc.h"
+#include "core/hle/kernel/svc_results.h"
 
 namespace Kernel::Svc {
 
@@ -64,14 +65,10 @@ Result WaitSynchronization(Core::System& system, int32_t* out_index, u64 user_ha
 
     // Copy user handles.
     if (num_handles > 0) {
-        // Ensure we can try to get the handles.
-        R_UNLESS(GetCurrentMemory(kernel).IsValidVirtualAddressRange(
-                     user_handles, static_cast<u64>(sizeof(Handle) * num_handles)),
-                 ResultInvalidPointer);
-
         // Get the handles.
-        GetCurrentMemory(kernel).ReadBlock(user_handles, handles.data(),
-                                           sizeof(Handle) * num_handles);
+        R_UNLESS(GetCurrentMemory(kernel).ReadBlock(user_handles, handles.data(),
+                                                    sizeof(Handle) * num_handles),
+                 ResultInvalidPointer);
 
         // Convert the handles to objects.
         R_UNLESS(handle_table.GetMultipleObjects<KSynchronizationObject>(