[scudo] Change secondary StatsAllocated update

[cferris]

Summary

In the secondary allocation routine, the StatsAllocated stat is
increased by BlockSize. However, in the deallocate routine, the
stat subtract uses CommitSize. CommitSize can be bigger than BlockSize
so this can lead to a negative calculated stat. Since the stats
are not guaranteed to be completely accurate, just add CommitSize
during allocation.

[Chia-hungDuan]

compiler-rt/lib/scudo/standalone/secondary.h

529

Nice catch! I think we may also want to update this to H->CommitSize.

[cferris]

Removed the BlockSize parameter and change all references to it
to H->CommitSize.

[cferris]

compiler-rt/lib/scudo/standalone/secondary.h

529

Did this and removed the comment since it doesn't make sense any more.

compiler-rt/lib/scudo/standalone/secondary.h

if (Cache.retrieve(Options, Size, Alignment, &H, &Zeroed)) {
       void *Ptr = reinterpret_cast<void *>(PtrInt);
       if (FillContents && !Zeroed)
         memset(Ptr, FillContents == ZeroFill ? 0 : PatternFillByte,
                BlockEnd - PtrInt);
       const uptr BlockSize = BlockEnd - HInt;
       {
         ScopedLock L(Mutex);
         InUseBlocks.push_back(H);
         AllocatedBytes += BlockSize;
         NumberOfAllocs++;
-        Stats.add(StatAllocated, BlockSize);
+        // Use H->CommitSize since on deallocate it's hard to recalculate
+        // the BlockSize to update the stats properly.
+        Stats.add(StatAllocated, H->CommitSize);
         Stats.add(StatMapped, H->MemMap.getCapacity());
       }
       return Ptr;
     }
   }
 
   ReservedMemoryT ReservedMemory;
   const uptr MapSize = RoundedSize + 2 * PageSize;