From d7c532d8894ce806c9af13b8dd3eec975642b348 Mon Sep 17 00:00:00 2001 From: comex Date: Sat, 1 Jul 2023 15:00:39 -0700 Subject: 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. --- src/video_core/query_cache.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'src/video_core/query_cache.h') diff --git a/src/video_core/query_cache.h b/src/video_core/query_cache.h index 1528cc1dd..7047e2e63 100644 --- a/src/video_core/query_cache.h +++ b/src/video_core/query_cache.h @@ -103,7 +103,9 @@ public: explicit QueryCacheBase(VideoCore::RasterizerInterface& rasterizer_, Core::Memory::Memory& cpu_memory_) : rasterizer{rasterizer_}, - cpu_memory{cpu_memory_}, streams{{CounterStream{static_cast(*this), + // Use reinterpret_cast instead of static_cast as workaround for + // UBSan bug (https://github.com/llvm/llvm-project/issues/59060) + cpu_memory{cpu_memory_}, streams{{CounterStream{reinterpret_cast(*this), VideoCore::QueryType::SamplesPassed}}} { (void)slot_async_jobs.insert(); // Null value } -- cgit v1.2.3