Tacet
9ed20568e7
This commit introduces basic annotations for `std::basic_string`, mirroring the approach used in `std::vector` and `std::deque`. Initially, only long strings with the default allocator will be annotated. Short strings (_SSO - short string optimization_) and strings with non-default allocators will be annotated in the near future, with separate commits dedicated to enabling them. The process will be similar to the workflow employed for enabling annotations in `std::deque`. **Please note**: these annotations function effectively only when libc++ and libc++abi dylibs are instrumented (with ASan). This aligns with the prevailing behavior of Memory Sanitizer. To avoid breaking everything, this commit also appends `_LIBCPP_INSTRUMENTED_WITH_ASAN` to `__config_site` whenever libc++ is compiled with ASan. If this macro is not defined, string annotations are not enabled. However, linking a binary that does **not** annotate strings with a dynamic library that annotates strings, is not permitted. Originally proposed here: https://reviews.llvm.org/D132769 Related patches on Phabricator: - Turning on annotations for short strings: https://reviews.llvm.org/D147680 - Turning on annotations for all allocators: https://reviews.llvm.org/D146214 This PR is a part of a series of patches extending AddressSanitizer C++ container overflow detection capabilities by adding annotations, similar to those existing in `std::vector` and `std::deque` collections. These enhancements empower ASan to effectively detect instances where the instrumented program attempts to access memory within a collection's internal allocation that remains unused. This includes cases where access occurs before or after the stored elements in `std::deque`, or between the `std::basic_string`'s size (including the null terminator) and capacity bounds. The introduction of these annotations was spurred by a real-world software bug discovered by Trail of Bits, involving an out-of-bounds memory access during the comparison of two strings using the `std::equals` function. This function was taking iterators (`iter1_begin`, `iter1_end`, `iter2_begin`) to perform the comparison, using a custom comparison function. When the `iter1` object exceeded the length of `iter2`, an out-of-bounds read could occur on the `iter2` object. Container sanitization, upon enabling these annotations, would effectively identify and flag this potential vulnerability. This Pull Request introduces basic annotations for `std::basic_string`. Long strings exhibit structural similarities to `std::vector` and will be annotated accordingly. Short strings are already implemented, but will be turned on separately in a forthcoming commit. Look at [a comment](https://github.com/llvm/llvm-project/pull/72677#issuecomment-1850554465) below to read about SSO issues at current moment. Due to the functionality introduced in [D132522](https://github.com/llvm/llvm-project/commit/dd1b7b797a116eed588fd752fbe61d34deeb24e4), the `__sanitizer_annotate_contiguous_container` function now offers compatibility with all allocators. However, enabling this support will be done in a subsequent commit. For the time being, only strings with the default allocator will be annotated. If you have any questions, please email: - advenam.tacet@trailofbits.com - disconnect3d@trailofbits.com
77 lines
2.3 KiB
C++
77 lines
2.3 KiB
C++
//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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// <string>
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// basic_string<charT,traits,Allocator>& append(const charT* s); // constexpr since C++20
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#include <string>
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#include <stdexcept>
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#include <cassert>
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#include "test_macros.h"
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#include "min_allocator.h"
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#include "asan_testing.h"
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template <class S>
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TEST_CONSTEXPR_CXX20 void test(S s, const typename S::value_type* str, S expected) {
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s.append(str);
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LIBCPP_ASSERT(s.__invariants());
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assert(s == expected);
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LIBCPP_ASSERT(is_string_asan_correct(s));
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}
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template <class S>
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TEST_CONSTEXPR_CXX20 void test_string() {
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test(S(), "", S());
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test(S(), "12345", S("12345"));
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test(S(), "12345678901234567890", S("12345678901234567890"));
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test(S("12345"), "", S("12345"));
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test(S("12345"), "12345", S("1234512345"));
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test(S("12345"), "1234567890", S("123451234567890"));
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test(S("12345678901234567890"), "", S("12345678901234567890"));
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test(S("12345678901234567890"), "12345", S("1234567890123456789012345"));
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test(S("12345678901234567890"), "12345678901234567890", S("1234567890123456789012345678901234567890"));
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}
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TEST_CONSTEXPR_CXX20 bool test() {
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test_string<std::string>();
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#if TEST_STD_VER >= 11
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test_string<std::basic_string<char, std::char_traits<char>, min_allocator<char>>>();
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test_string<std::basic_string<char, std::char_traits<char>, safe_allocator<char>>>();
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#endif
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{ // test appending to self
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typedef std::string S;
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S s_short = "123/";
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S s_long = "Lorem ipsum dolor sit amet, consectetur/";
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s_short.append(s_short.c_str());
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assert(s_short == "123/123/");
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s_short.append(s_short.c_str());
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assert(s_short == "123/123/123/123/");
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s_short.append(s_short.c_str());
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assert(s_short == "123/123/123/123/123/123/123/123/");
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s_long.append(s_long.c_str());
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assert(s_long == "Lorem ipsum dolor sit amet, consectetur/Lorem ipsum dolor sit amet, consectetur/");
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}
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return true;
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}
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int main(int, char**) {
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test();
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#if TEST_STD_VER > 17
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static_assert(test());
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#endif
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return 0;
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}
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