当我尝试使用std::vector<std::aligned_storage<sizeof(T), alignof(T)>> vec
进行操作时,地址清理程序变得异常:
1.有时,将新的::new(&vec[some_index]) T(std::forward<Args>(args)...)
放置在向量vec
的元素vec[some_index]
处工作良好,除非T
是小的std::string
std::destroy_at(std::launder(reinterpret_cast<T *>(&vec[some_index])))
根本不起作用,而且as cppreference says:“如果T
是数组类型,则程序是病态的”-而std::aligned_storage
上的cppreference示例在std::aligned_storage
的示例中很好地使用了std::destroy_at
。
提供了以下示例:
#include <string>
#include <type_traits>
#include <vector>
#include <new>
#include <memory>
int main() {
std::vector<std::aligned_storage<sizeof(std::string), alignof(std::string)>>
vec(1);
::new(&vec[0]) std::string(334, 'a'); // Fine
std::destroy_at(std::launder(reinterpret_cast<std::string *>(&vec[0]))); // Still fine
::new(&vec[0]) std::string(334, 'a'); // Okay
std::destroy_at(std::launder(reinterpret_cast<std::string *>(&vec[0]))); // Still okay
::new(&vec[0]) std::string(3, 'a'); // Cool
std::destroy_at(std::launder(reinterpret_cast<std::string *>(&vec[0]))); // Breaks the code at previous line
}
asan输出如下:
==22152==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x602000000020 at pc 0x7fa1a8c27f26 bp 0x7fff54d86410 sp 0x7fff54d85bb8
WRITE of size 3 at 0x602000000020 thread T0
#0 0x7fa1a8c27f25 in __interceptor_memset ../../../../src/libsanitizer/sanitizer_common/sanitizer_common_interceptors.inc:795
#1 0x7fa1a8b4ef56 in std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_M_construct(unsigned long, char) (/lib/x86_64-linux-gnu/libstdc++.so.6+0x142f56)
#2 0x557bafbcb8a5 in std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::basic_string<std::allocator<char> >(unsigned long, char, std::allocator<char> const&) /usr/include/c++/10/bits/basic_string.h:542
#3 0x557bafbcb613 in main testing.cpp:14
#4 0x7fa1a86d4082 in __libc_start_main ../csu/libc-start.c:308
#5 0x557bafbcb34d in _start (/home/valery/repos/effective-cpp/tasks/a.out+0x234d)
0x602000000020 is located 15 bytes to the right of 1-byte region [0x602000000010,0x602000000011)
allocated by thread T0 here:
#0 0x7fa1a8c9ff27 in operator new(unsigned long) ../../../../src/libsanitizer/asan/asan_new_delete.cpp:99
#1 0x557bafbcc532 in __gnu_cxx::new_allocator<std::aligned_storage<32ul, 8ul> >::allocate(unsigned long, void const*) /usr/include/c++/10/ext/new_allocator.h:115
#2 0x557bafbcc39d in std::allocator_traits<std::allocator<std::aligned_storage<32ul, 8ul> > >::allocate(std::allocator<std::aligned_storage<32ul, 8ul> >&, unsigned long) /usr/include/c++/10/bits/alloc_traits.h:460
#3 0x557bafbcc2d7 in std::_Vector_base<std::aligned_storage<32ul, 8ul>, std::allocator<std::aligned_storage<32ul, 8ul> > >::_M_allocate(unsigned long) /usr/include/c++/10/bits/stl_vector.h:346
#4 0x557bafbcc034 in std::_Vector_base<std::aligned_storage<32ul, 8ul>, std::allocator<std::aligned_storage<32ul, 8ul> > >::_M_create_storage(unsigned long) /usr/include/c++/10/bits/stl_vector.h:361
#5 0x557bafbcbc70 in std::_Vector_base<std::aligned_storage<32ul, 8ul>, std::allocator<std::aligned_storage<32ul, 8ul> > >::_Vector_base(unsigned long, std::allocator<std::aligned_storage<32ul, 8ul> > const&) /usr/include/c++/10/bits/stl_vector.h:305
#6 0x557bafbcb952 in std::vector<std::aligned_storage<32ul, 8ul>, std::allocator<std::aligned_storage<32ul, 8ul> > >::vector(unsigned long, std::allocator<std::aligned_storage<32ul, 8ul> > const&) /usr/include/c++/10/bits/stl_vector.h:511
#7 0x557bafbcb4e8 in main testing.cpp:9
#8 0x7fa1a86d4082 in __libc_start_main ../csu/libc-start.c:308
SUMMARY: AddressSanitizer: heap-buffer-overflow ../../../../src/libsanitizer/sanitizer_common/sanitizer_common_interceptors.inc:795 in __interceptor_memset
Shadow bytes around the buggy address:
0x0c047fff7fb0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0c047fff7fc0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0c047fff7fd0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0c047fff7fe0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0c047fff7ff0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x0c047fff8000: fa fa 01 fa[fa]fa fa fa fa fa fa fa fa fa fa fa
0x0c047fff8010: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c047fff8020: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c047fff8030: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c047fff8040: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c047fff8050: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
Shadow byte legend (one shadow byte represents 8 application bytes):
Addressable: 00
Partially addressable: 01 02 03 04 05 06 07
Heap left redzone: fa
Freed heap region: fd
Stack left redzone: f1
Stack mid redzone: f2
Stack right redzone: f3
Stack after return: f5
Stack use after scope: f8
Global redzone: f9
Global init order: f6
Poisoned by user: f7
Container overflow: fc
Array cookie: ac
Intra object redzone: bb
ASan internal: fe
Left alloca redzone: ca
Right alloca redzone: cb
Shadow gap: cc
==22152==ABORTING
我的设置是x86_64 Ubuntu 20.04上的g++-10
/clang++-12
。
我找不到任何关于std::aligned_storage
的信息,可能是因为它已经过时了。
1条答案
按热度按时间dtcbnfnu1#
如上所述,问题在于
std::vector<std::aligned_storage<sizeof(T),alignof(T)>>
不正确。std::aligned_storage<size,size>
有一个嵌套的typedeftype
,它具有您想要的属性。你想要的是
std::vector<std::aligned_storage<sizeof(T),alignof(T)>::type>