[PATCH] Add AddressSanitizer annotations to std::vector

[Jonathan Wakely]

On 06/07/17 20:23 +0300, Ivan Baravy wrote:
>On 07/05/2017 10:00 PM, Jonathan Wakely wrote:
>> This patch adds AddressSanitizer annotations to std::vector, so that
>> ASan can detect out-of-bounds accesses to the unused capacity of a
>> vector. e.g.
>>
>>   std::vector<int> v(2);
>>   int* p = v.data();
>>   v.pop_back();
>>   return p[1];  // ERROR
>>
>> This cannot be detected by Debug Mode, but with these annotations ASan
>> knows that only v.data()[0] is valid and will give an error.
>>
>> The annotations are only enabled for vector<T, std::allocator<T>> and
>> only when std::allocator's base class is either malloc_allocator or
>> new_allocator. For other allocators the memory might not come from the
>> freestore and so isn't tracked by ASan.
>>
>> Something similar has been on the google branches for some time:
>> https://gcc.gnu.org/viewcvs/gcc?view=revision&revision=207517
>> This patch is a complete rewrite from scratch, because the google code
>> was not exception safe. If an exception happened while appending
>> elements to a vector, so that the size didn't change, the google code
>> did not undo the annotation for the increased size. It also didn't
>> annotate before deallocating, to mark the unused capacity as valid
>> again.
>>
>> We can probably do similar annotations for std::deque, so that
>> partially filled pages are annotated. I also have a patch for
>> shared_ptr so that objects created by make_shared can be marked as
>> invalid after they're destroyed.
>
>Could you share your plans on sanitization of other standard containers?
>My particular interest is in std::string which I'm working on now.

I might make similar changes to std::deque, but not immediately. I
have no plans to do anything with std::string (because you said you're
working on it).

>Also, will you backport the feature to GCC7 and GCC6?

No, probably not.

>> 	* config/allocator/malloc_allocator_base.h [__SANITIZE_ADDRESS__]
>> 	(_GLIBCXX_SANITIZE_STD_ALLOCATOR): Define.
>> 	* config/allocator/new_allocator_base.h [__SANITIZE_ADDRESS__]
>> 	(_GLIBCXX_SANITIZE_STD_ALLOCATOR): Define.
>> 	* include/bits/stl_vector.h [_GLIBCXX_SANITIZE_STD_ALLOCATOR]
>> 	(_Vector_impl::_Asan, _Vector_impl::_Asan::_Reinit)
>> 	(_Vector_impl::_Asan::_Grow, _GLIBCXX_ASAN_ANNOTATE_REINIT)
>> 	(_GLIBCXX_ASAN_ANNOTATE_GROW, _GLIBCXX_ASAN_ANNOTATE_GREW)
>> 	(_GLIBCXX_ASAN_ANNOTATE_SHRINK, _GLIBCXX_ASAN_ANNOTATE_BEFORE_DEALLOC):
>> 	Define annotation helper types and macros.
>> 	(vector::~vector, vector::push_back, vector::pop_back)
>> 	(vector::_M_erase_at_end): Add annotations.
>> 	* include/bits/vector.tcc (vector::reserve, vector::emplace_back)
>> 	(vector::insert, vector::_M_erase, vector::operator=)
>> 	(vector::_M_fill_assign, vector::_M_assign_aux)
>> 	(vector::_M_insert_rval, vector::_M_emplace_aux)
>> 	(vector::_M_insert_aux, vector::_M_realloc_insert)
>> 	(vector::_M_fill_insert, vector::_M_default_append)
>> 	(vector::_M_shrink_to_fit, vector::_M_range_insert): Annotate.
>>
>> Tested x86_64-linux (using -fsanitize=address, with some local patches
>> to the testsuite) and powerpc64le-linux.
>>
>> I plan to commit this to trunk tomorrow.
>>