Fixes and workarounds to make UBSan happier on macOS

There are still some other issues not addressed here, but it's a start.

Workarounds for false-positive reports:

- `RasterizerAccelerated`: Put a gigantic array behind a `unique_ptr`,
  because UBSan has a [hardcoded limit](https://stackoverflow.com/questions/64531383/c-runtime-error-using-fsanitize-undefined-object-has-a-possibly-invalid-vp)
  of how big it thinks objects can be, specifically when dealing with
  offset-to-top values used with multiple inheritance.  Hopefully this
  doesn't have a performance impact.

- `QueryCacheBase::QueryCacheBase`: Avoid an operation that UBSan thinks
  is UB even though it at least arguably isn't.  See the link in the
  comment for more information.

Fixes for correct reports:

- `PageTable`, `Memory`: Use `uintptr_t` values instead of pointers to
  avoid UB from pointer overflow (when pointer arithmetic wraps around
  the address space).

- `KScheduler::Reload`: `thread->GetOwnerProcess()` can be `nullptr`;
  avoid calling methods on it in this case.  (The existing code returns
  a garbage reference to a field, which is then passed into
  `LoadWatchpointArray`, and apparently it's never used, so it's
  harmless in practice but still triggers UBSan.)

- `KAutoObject::Close`: This function calls `this->Destroy()`, which
  overwrites the beginning of the object with junk (specifically a free
  list pointer).  Then it calls `this->UnregisterWithKernel()`.  UBSan
  complains about a type mismatch because the vtable has been
  overwritten, and I believe this is indeed UB.  `UnregisterWithKernel`
  also loads `m_kernel` from the 'freed' object, which seems to be
  technically safe (the overwriting doesn't extend as far as that
  field), but seems dubious.  Switch to a `static` method and load
  `m_kernel` in advance.

1 files changed, 17 insertions, 13 deletions

diff --git a/src/core/memory.cpp b/src/core/memory.cpp
index 805963178..7538c1d23 100644
--- a/src/core/memory.cpp
+++ b/src/core/memory.cpp
@@ -73,7 +73,7 @@ struct Memory::Impl {
             return {};
         }
 
-        return system.DeviceMemory().GetPointer<u8>(paddr) + vaddr;
+        return system.DeviceMemory().GetPointer<u8>(paddr + vaddr);
     }
 
     [[nodiscard]] u8* GetPointerFromDebugMemory(u64 vaddr) const {
@@ -84,7 +84,7 @@ struct Memory::Impl {
             return {};
         }
 
-        return system.DeviceMemory().GetPointer<u8>(paddr) + vaddr;
+        return system.DeviceMemory().GetPointer<u8>(paddr + vaddr);
     }
 
     u8 Read8(const Common::ProcessAddress addr) {
@@ -204,7 +204,8 @@ struct Memory::Impl {
                 break;
             }
             case Common::PageType::Memory: {
-                u8* mem_ptr = pointer + page_offset + (page_index << YUZU_PAGEBITS);
+                u8* mem_ptr =
+                    reinterpret_cast<u8*>(pointer + page_offset + (page_index << YUZU_PAGEBITS));
                 on_memory(copy_amount, mem_ptr);
                 break;
             }
@@ -448,7 +449,7 @@ struct Memory::Impl {
                     break;
                 case Common::PageType::Memory:
                     current_page_table->pointers[vaddr >> YUZU_PAGEBITS].Store(
-                        nullptr, Common::PageType::DebugMemory);
+                        0, Common::PageType::DebugMemory);
                     break;
                 default:
                     UNREACHABLE();
@@ -466,7 +467,8 @@ struct Memory::Impl {
                 case Common::PageType::DebugMemory: {
                     u8* const pointer{GetPointerFromDebugMemory(vaddr & ~YUZU_PAGEMASK)};
                     current_page_table->pointers[vaddr >> YUZU_PAGEBITS].Store(
-                        pointer - (vaddr & ~YUZU_PAGEMASK), Common::PageType::Memory);
+                        reinterpret_cast<uintptr_t>(pointer) - (vaddr & ~YUZU_PAGEMASK),
+                        Common::PageType::Memory);
                     break;
                 }
                 default:
@@ -506,7 +508,7 @@ struct Memory::Impl {
                 case Common::PageType::DebugMemory:
                 case Common::PageType::Memory:
                     current_page_table->pointers[vaddr >> YUZU_PAGEBITS].Store(
-                        nullptr, Common::PageType::RasterizerCachedMemory);
+                        0, Common::PageType::RasterizerCachedMemory);
                     break;
                 case Common::PageType::RasterizerCachedMemory:
                     // There can be more than one GPU region mapped per CPU region, so it's common
@@ -534,10 +536,11 @@ struct Memory::Impl {
                         // pagetable after unmapping a VMA. In that case the underlying VMA will no
                         // longer exist, and we should just leave the pagetable entry blank.
                         current_page_table->pointers[vaddr >> YUZU_PAGEBITS].Store(
-                            nullptr, Common::PageType::Unmapped);
+                            0, Common::PageType::Unmapped);
                     } else {
                         current_page_table->pointers[vaddr >> YUZU_PAGEBITS].Store(
-                            pointer - (vaddr & ~YUZU_PAGEMASK), Common::PageType::Memory);
+                            reinterpret_cast<uintptr_t>(pointer) - (vaddr & ~YUZU_PAGEMASK),
+                            Common::PageType::Memory);
                     }
                     break;
                 }
@@ -584,7 +587,7 @@ struct Memory::Impl {
                        "Mapping memory page without a pointer @ {:016x}", base * YUZU_PAGESIZE);
 
             while (base != end) {
-                page_table.pointers[base].Store(nullptr, type);
+                page_table.pointers[base].Store(0, type);
                 page_table.backing_addr[base] = 0;
                 page_table.blocks[base] = 0;
                 base += 1;
@@ -593,7 +596,8 @@ struct Memory::Impl {
             auto orig_base = base;
             while (base != end) {
                 auto host_ptr =
-                    system.DeviceMemory().GetPointer<u8>(target) - (base << YUZU_PAGEBITS);
+                    reinterpret_cast<uintptr_t>(system.DeviceMemory().GetPointer<u8>(target)) -
+                    (base << YUZU_PAGEBITS);
                 auto backing = GetInteger(target) - (base << YUZU_PAGEBITS);
                 page_table.pointers[base].Store(host_ptr, type);
                 page_table.backing_addr[base] = backing;
@@ -619,8 +623,8 @@ struct Memory::Impl {
 
         // Avoid adding any extra logic to this fast-path block
         const uintptr_t raw_pointer = current_page_table->pointers[vaddr >> YUZU_PAGEBITS].Raw();
-        if (u8* const pointer = Common::PageTable::PageInfo::ExtractPointer(raw_pointer)) {
-            return &pointer[vaddr];
+        if (const uintptr_t pointer = Common::PageTable::PageInfo::ExtractPointer(raw_pointer)) {
+            return reinterpret_cast<u8*>(pointer + vaddr);
         }
         switch (Common::PageTable::PageInfo::ExtractType(raw_pointer)) {
         case Common::PageType::Unmapped:
@@ -814,7 +818,7 @@ bool Memory::IsValidVirtualAddress(const Common::ProcessAddress vaddr) const {
         return false;
     }
     const auto [pointer, type] = page_table.pointers[page].PointerType();
-    return pointer != nullptr || type == Common::PageType::RasterizerCachedMemory ||
+    return pointer != 0 || type == Common::PageType::RasterizerCachedMemory ||
            type == Common::PageType::DebugMemory;
 }