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.