NetKDRequestDevice: Fix nullptr dereference crash

Keep a shared_ptr to NetKDTimeDevice inside NetKDRequestDevice.

This allows the KDDownload task to finish its work without potentially
trying to dereference nullptr, which can potentially come from either
GetIOS() or GetDeviceByName() if EmulationKernel's destructor has
started running.

3 files changed, 16 insertions, 14 deletions

diff --git a/Source/Core/Core/IOS/IOS.cpp b/Source/Core/Core/IOS/IOS.cpp
index 9e73644a22..35c06626a3 100644
--- a/Source/Core/Core/IOS/IOS.cpp
+++ b/Source/Core/Core/IOS/IOS.cpp
@@ -577,8 +577,11 @@ void EmulationKernel::AddStaticDevices()
   }
   if (HasFeature(features, Feature::KD))
   {
-    AddDevice(std::make_unique<NetKDRequestDevice>(*this, "/dev/net/kd/request"));
-    AddDevice(std::make_unique<NetKDTimeDevice>(*this, "/dev/net/kd/time"));
+    constexpr auto time_device_name = "/dev/net/kd/time";
+    AddDevice(std::make_unique<NetKDTimeDevice>(*this, time_device_name));
+    const auto time_device =
+        std::static_pointer_cast<NetKDTimeDevice>(GetDeviceByName(time_device_name));
+    AddDevice(std::make_unique<NetKDRequestDevice>(*this, "/dev/net/kd/request", time_device));
   }
   if (HasFeature(features, Feature::NCD))
   {
diff --git a/Source/Core/Core/IOS/Network/KD/NetKDRequest.cpp b/Source/Core/Core/IOS/Network/KD/NetKDRequest.cpp
index c2420a9dd1..56bda89f65 100644
--- a/Source/Core/Core/IOS/Network/KD/NetKDRequest.cpp
+++ b/Source/Core/Core/IOS/Network/KD/NetKDRequest.cpp
@@ -153,9 +153,10 @@ s32 NWC24MakeUserID(u64* nwc24_id, u32 hollywood_id, u16 id_ctr, HardwareModel h
 }
 }  // Anonymous namespace
 
-NetKDRequestDevice::NetKDRequestDevice(EmulationKernel& ios, const std::string& device_name)
+NetKDRequestDevice::NetKDRequestDevice(EmulationKernel& ios, const std::string& device_name,
+                                       const std::shared_ptr<NetKDTimeDevice>& time_device)
     : EmulationDevice(ios, device_name), m_config{ios.GetFS()}, m_dl_list{ios.GetFS()},
-      m_send_list{ios.GetFS()}, m_friend_list{ios.GetFS()}
+      m_send_list{ios.GetFS()}, m_friend_list{ios.GetFS()}, m_time_device{time_device}
 {
   // Enable all NWC24 permissions
   m_scheduler_buffer[1] = Common::swap32(-1);
@@ -443,9 +444,7 @@ NWC24::ErrorCode NetKDRequestDevice::DetermineDownloadTask(u16* entry_index,
   // As the scheduler does not tell us which entry to download, we must determine that.
   // A correct entry is one that hasn't been downloaded the longest compared to other entries.
   // We first need current UTC.
-  const auto time_device =
-      std::static_pointer_cast<NetKDTimeDevice>(GetIOS()->GetDeviceByName("/dev/net/kd/time"));
-  const u64 current_utc = time_device->GetAdjustedUTC();
+  const u64 current_utc = m_time_device->GetAdjustedUTC();
   u64 lowest_timestamp = std::numeric_limits<u64>::max();
 
   for (u16 i = 0; i < static_cast<u16>(NWC24::NWC24Dl::MAX_ENTRIES); i++)
@@ -495,9 +494,7 @@ NWC24::ErrorCode NetKDRequestDevice::DetermineSubtask(u16 entry_index,
   if (m_dl_list.IsSubtaskDownloadDisabled(entry_index))
     return NWC24::WC24_ERR_DISABLED;
 
-  const auto time_device =
-      std::static_pointer_cast<NetKDTimeDevice>(GetIOS()->GetDeviceByName("/dev/net/kd/time"));
-  const u64 current_utc = time_device->GetAdjustedUTC();
+  const u64 current_utc = m_time_device->GetAdjustedUTC();
   for (u8 i = 0; i < 32; i++)
   {
     if (!m_dl_list.IsValidSubtask(entry_index, i))
@@ -647,9 +644,7 @@ NWC24::ErrorCode NetKDRequestDevice::KDDownload(const u16 entry_index,
 {
   bool success = false;
   Common::ScopeGuard state_guard([&] {
-    const auto time_device =
-        std::static_pointer_cast<NetKDTimeDevice>(GetIOS()->GetDeviceByName("/dev/net/kd/time"));
-    const u64 current_utc = time_device->GetAdjustedUTC();
+    const u64 current_utc = m_time_device->GetAdjustedUTC();
     if (success)
     {
       // Set the next download time to the dl_margin
diff --git a/Source/Core/Core/IOS/Network/KD/NetKDRequest.h b/Source/Core/Core/IOS/Network/KD/NetKDRequest.h
index 0fcd43f52d..848454fa71 100644
--- a/Source/Core/Core/IOS/Network/KD/NetKDRequest.h
+++ b/Source/Core/Core/IOS/Network/KD/NetKDRequest.h
@@ -4,6 +4,7 @@
 #pragma once
 
 #include <array>
+#include <memory>
 #include <queue>
 #include <string>
 
@@ -17,6 +18,7 @@
 #include "Core/IOS/Network/KD/Mail/WC24Send.h"
 #include "Core/IOS/Network/KD/NWC24Config.h"
 #include "Core/IOS/Network/KD/NWC24DL.h"
+#include "Core/IOS/Network/KD/NetKDTime.h"
 
 namespace IOS::HLE
 {
@@ -26,7 +28,8 @@ namespace IOS::HLE
 class NetKDRequestDevice : public EmulationDevice
 {
 public:
-  NetKDRequestDevice(EmulationKernel& ios, const std::string& device_name);
+  NetKDRequestDevice(EmulationKernel& ios, const std::string& device_name,
+                     const std::shared_ptr<NetKDTimeDevice>& time_device);
   IPCReply HandleNWC24DownloadNowEx(const IOCtlRequest& request);
   NWC24::ErrorCode KDDownload(const u16 entry_index, const std::optional<u8> subtask_id);
   IPCReply HandleNWC24CheckMailNow(const IOCtlRequest& request);
@@ -114,6 +117,7 @@ private:
   std::queue<AsyncReply> m_async_replies;
   u32 m_error_count = 0;
   std::array<u32, 256> m_scheduler_buffer{};
+  std::shared_ptr<NetKDTimeDevice> m_time_device;
   // TODO: Maybe move away from Common::HttpRequest?
   Common::HttpRequest m_http{std::chrono::minutes{1}};
   u32 m_download_span = 2;