[NFC][hwasan] Don't tag secondary allocations on free

[vitalybuka]

Summary

OnUnmap will tag it to zero anyway.

[fmayer]

compiler-rt/lib/hwasan/hwasan_allocator.cpp

378

can we put a debug assert that it's untagged here?

[fmayer]

Also nit: typo in commit message.

[vitalybuka]

compiler-rt/lib/hwasan/hwasan_allocator.cpp

378

We can't, as soon we call Deallocate, another thread can pick up the memory.

compiler-rt/lib/hwasan/hwasan_allocator.cpp

static void HwasanDeallocate(StackTrace *stack, void *tagged_ptr) {
   // poisoned.
   Thread *t = GetCurrentThread();
   if (flags()->max_free_fill_size > 0) {
     uptr fill_size =
         Min(TaggedSize(orig_size), (uptr)flags()->max_free_fill_size);
     internal_memset(aligned_ptr, flags()->free_fill_byte, fill_size);
   }
   if (in_taggable_region && flags()->tag_in_free && malloc_bisect(stack, 0) &&
-      atomic_load_relaxed(&hwasan_allocator_tagging_enabled)) {
+      atomic_load_relaxed(&hwasan_allocator_tagging_enabled) &&
+      allocator.FromPrimary(untagged_ptr) /* Secondary 0-tag and unmap.*/) {
     // Always store full 8-bit tags on free to maximize UAF detection.
     tag_t tag;
     if (t) {
       // Make sure we are not using a short granule tag as a poison tag. This
       // would make us attempt to read the memory on a UaF.
       // The tag can be zero if tagging is disabled on this thread.
       do {
         tag = t->GenerateRandomTag(/*num_bits=*/8);
if (t) {
     if (auto *ha = t->heap_allocations())
       ha->push({reinterpret_cast<uptr>(tagged_ptr), alloc_thread_id,
                 alloc_context_id, free_context_id,
                 static_cast<u32>(orig_size)});
   } else {
     SpinMutexLock l(&fallback_mutex);
     AllocatorCache *cache = &fallback_allocator_cache;
     allocator.Deallocate(cache, aligned_ptr);
   }
 }
 
 static void *HwasanReallocate(StackTrace *stack, void *tagged_ptr_old,
                               uptr new_size, uptr alignment) {
   void *untagged_ptr_old = UntagPtr(tagged_ptr_old);
   if (CheckInvalidFree(stack, untagged_ptr_old, tagged_ptr_old))
     return nullptr;
   void *tagged_ptr_new =