libcxx/include/__debug_utils/sanitizers.h

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

#ifndef _LIBCPP___LIBCXX_DEBUG_UTILS_SANITIZERS_H
#define _LIBCPP___LIBCXX_DEBUG_UTILS_SANITIZERS_H

#include <__config>
#include <__type_traits/integral_constant.h>
#include <__type_traits/is_constant_evaluated.h>

#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
#  pragma GCC system_header
#endif

// Within libc++, _LIBCPP_ENABLE_ASAN_CONTAINER_CHECKS determines whether the containers should
// provide ASAN container overflow checks. That setting attempts to honour ASAN's documented option
// __SANITIZER_DISABLE_CONTAINER_OVERFLOW__ which can be defined by users to disable container overflow
// checks.
//
// However, since parts of some containers (e.g. std::string) are compiled separately into the built
// library, there are caveats:
// - __SANITIZER_DISABLE_CONTAINER_OVERFLOW__ can't always be honoured, i.e. if the built library
//   was compiled with ASAN container checks, it's impossible to turn them off afterwards. We diagnose
//   this with an error to avoid the proliferation of invalid configurations that appear to work.
//
// - The container overflow checks themselves are not always available even when the user is compiling
//   with -fsanitize=address. If a container is compiled separately like std::string, it can't provide
//   container checks unless the separately compiled code was built with container checks enabled. These
//   containers need to also conditionalize whether they provide overflow checks on `_LIBCPP_INSTRUMENTED_WITH_ASAN`.
#if __has_feature(address_sanitizer) && !defined(__SANITIZER_DISABLE_CONTAINER_OVERFLOW__)
#  define _LIBCPP_ENABLE_ASAN_CONTAINER_CHECKS 1
#else
#  define _LIBCPP_ENABLE_ASAN_CONTAINER_CHECKS 0
#endif

#if _LIBCPP_INSTRUMENTED_WITH_ASAN && !_LIBCPP_ENABLE_ASAN_CONTAINER_CHECKS
#  error "We can't disable ASAN container checks when libc++ has been built with ASAN container checks enabled"
#endif

#if _LIBCPP_ENABLE_ASAN_CONTAINER_CHECKS

extern "C" {
_LIBCPP_EXPORTED_FROM_ABI void
__sanitizer_annotate_contiguous_container(const void*, const void*, const void*, const void*);
_LIBCPP_EXPORTED_FROM_ABI void __sanitizer_annotate_double_ended_contiguous_container(
    const void*, const void*, const void*, const void*, const void*, const void*);
_LIBCPP_EXPORTED_FROM_ABI int
__sanitizer_verify_double_ended_contiguous_container(const void*, const void*, const void*, const void*);
}

#endif // _LIBCPP_ENABLE_ASAN_CONTAINER_CHECKS

_LIBCPP_BEGIN_NAMESPACE_STD

// ASan choices
#if _LIBCPP_ENABLE_ASAN_CONTAINER_CHECKS
#  define _LIBCPP_HAS_ASAN_CONTAINER_ANNOTATIONS_FOR_ALL_ALLOCATORS 1
#endif

#ifdef _LIBCPP_HAS_ASAN_CONTAINER_ANNOTATIONS_FOR_ALL_ALLOCATORS
// __asan_annotate_container_with_allocator determines whether containers with custom allocators are annotated. This is
// a public customization point to disable annotations if the custom allocator assumes that the memory isn't poisoned.
// See the https://libcxx.llvm.org/UsingLibcxx.html#turning-off-asan-annotation-in-containers for more information.
template <class _Alloc>
struct __asan_annotate_container_with_allocator : true_type {};
#endif

// Annotate a double-ended contiguous range.
// - [__first_storage, __last_storage) is the allocated memory region,
// - [__first_old_contained, __last_old_contained) is the previously allowed (unpoisoned) range, and
// - [__first_new_contained, __last_new_contained) is the new allowed (unpoisoned) range.
template <class _Allocator>
_LIBCPP_HIDE_FROM_ABI void __annotate_double_ended_contiguous_container(
    const void* __first_storage,
    const void* __last_storage,
    const void* __first_old_contained,
    const void* __last_old_contained,
    const void* __first_new_contained,
    const void* __last_new_contained) {
#if !_LIBCPP_ENABLE_ASAN_CONTAINER_CHECKS
  (void)__first_storage;
  (void)__last_storage;
  (void)__first_old_contained;
  (void)__last_old_contained;
  (void)__first_new_contained;
  (void)__last_new_contained;
#else
  if (__asan_annotate_container_with_allocator<_Allocator>::value && __first_storage != nullptr)
    __sanitizer_annotate_double_ended_contiguous_container(
        __first_storage,
        __last_storage,
        __first_old_contained,
        __last_old_contained,
        __first_new_contained,
        __last_new_contained);
#endif
}

// Annotate a contiguous range.
// [__first_storage, __last_storage) is the allocated memory region,
// __old_last_contained is the previously last allowed (unpoisoned) element, and
// __new_last_contained is the new last allowed (unpoisoned) element.
template <class _Allocator>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 void __annotate_contiguous_container(
    const void* __first_storage,
    const void* __last_storage,
    const void* __old_last_contained,
    const void* __new_last_contained) {
#if !_LIBCPP_ENABLE_ASAN_CONTAINER_CHECKS
  (void)__first_storage;
  (void)__last_storage;
  (void)__old_last_contained;
  (void)__new_last_contained;
#else
  if (!__libcpp_is_constant_evaluated() && __asan_annotate_container_with_allocator<_Allocator>::value &&
      __first_storage != nullptr)
    __sanitizer_annotate_contiguous_container(
        __first_storage, __last_storage, __old_last_contained, __new_last_contained);
#endif
}

_LIBCPP_END_NAMESPACE_STD

#endif // _LIBCPP___LIBCXX_DEBUG_UTILS_SANITIZERS_H