Commit b5cbb354 authored by Ilya Biryukov's avatar Ilya Biryukov Committed by Tobias Hieta
Browse files

[libc++] Use correct size for deallocation of arrays in shared_ptr (#68233) 

Fixes #68051.

Current implementation passes the number of `_AlignedStorage` objects
when it calls to `allocate` and the number of **bytes** on `deallocate`.
This only applies to allocations that allocate control block and the
storage together, i.e. `make_shared` and `allocate_shared`.

Found by ASan under Clang combined with `-fsized-deallocation`.

(cherry picked from commit f722db02)
parent e6de86cb

libcxx/include/__memory/shared_ptr.h

+3 −2
Original line number Diff line number Diff line
@@ -1134,7 +1134,8 @@ private: 
        __alloc_.~_Alloc();

        size_t __size = __unbounded_array_control_block::__bytes_for(__count_);

        _AlignedStorage* __storage = reinterpret_cast<_AlignedStorage*>(this);

        allocator_traits<_StorageAlloc>::deallocate(__tmp, _PointerTraits::pointer_to(*__storage), __size);

        allocator_traits<_StorageAlloc>::deallocate(

            __tmp, _PointerTraits::pointer_to(*__storage), __size / sizeof(_AlignedStorage));

    }



    _LIBCPP_NO_UNIQUE_ADDRESS _Alloc __alloc_;
@@ -1217,7 +1218,7 @@ private: 


        _ControlBlockAlloc __tmp(__alloc_);

        __alloc_.~_Alloc();

        allocator_traits<_ControlBlockAlloc>::deallocate(__tmp, _PointerTraits::pointer_to(*this), sizeof(*this));

        allocator_traits<_ControlBlockAlloc>::deallocate(__tmp, _PointerTraits::pointer_to(*this), 1);

    }



    _LIBCPP_NO_UNIQUE_ADDRESS _Alloc __alloc_;

libcxx/test/libcxx/memory/shared_ptr_array.pass.cpp

0 → 100644
+27 −0
Original line number Diff line number Diff line 
//===----------------------------------------------------------------------===//

//

// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.

// See https://llvm.org/LICENSE.txt for license information.

// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

//

//===----------------------------------------------------------------------===//

//



// UNSUPPORTED: c++03, c++11, c++14, c++17

// REQUIRES: -fsized-deallocation

// ADDITIONAL_COMPILE_FLAGS: -fsized-deallocation



// This test will fail with ASan if the implementation passes different sizes

// to corresponding allocation and deallocation functions.



#include <memory>



int main(int, char**) {

  std::allocate_shared<int[]>(std::allocator<int>{}, 10);

  std::make_shared<int[]>(10);



  std::allocate_shared<int[10]>(std::allocator<int>{});

  std::make_shared<int[10]>();



  return 0;

}