[ASan][libc++] std::basic_string annotations #72677

This commit turns on basic annotations for std::basic_string, similar to those in std::vector and std::deque. Originally proposed here: https://reviews.llvm.org/D132769 Related patches: Turning on annotations for short strings: https://reviews.llvm.org/D147680 Turning on annotations for all allocators: https://reviews.llvm.org/D146214 This revision 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, to std::string and std::deque collections. These changes allow ASan to detect cases when the instrumented program accesses memory which is internally allocated by the collection but is still not in-use (accesses before or after the stored elements for std::deque, or between the size and capacity bounds for std::string). The motivation for the research and those changes was a bug, found by Trail of Bits, in a real code where an out-of-bounds read could happen as two strings were compared via a std::equals function that took iter1_begin, iter1_end, iter2_begin iterators (with a custom comparison function). When object iter1 was longer than iter2, read out-of-bounds on iter2 could happen. Container sanitization would detect it. This Pull Request adds annotations for `std::basic_string`. Long string is very similar to std::vector, and therefore works well with `__sanitizer_annotate_contiguous_container` from LLVM 15 and therefore annotations works if that implementation is compiled with previous LLVM. However, only the standard allocator is supported. As D132522 extended possibilities of `__sanitizer_annotate_contiguous_container`, now annotations may be supported with all allocators, but that support will be added in a next PR. Only strings with default allocator are annotated with that commit. If you have any questions, please email: - advenam.tacet@trailofbits.com - disconnect3d@trailofbits.com

This commit refactors the ASan annotation function to reduce unnecessary code duplication. Suggested here: llvm#73043 Related PR: llvm#74023

Requested changes for existing code. Additional changes related to dylibs in the next commit. This commit extends a few more tests to cover long strings in more situations.

…annotations * CMake files are updated to automatically add the `_LIBCPP_INSTRUMENTED_WITH_ASAN` macro to `__config_site`. This macro is used to inform the compiler (in header files) that the library has been built with ASan and is instrumented for memory safety checks. * The `-D_LIBCPP_INSTRUMENTED_WITH_ASAN` flag is added to the libc++ compilation command when building with ASan. This flag ensures that basic_string annotations are included in the binary, which are needed for ASan to track memory usage correctly. * The string file is updated to use string annotations from headers if and only if the code is compiled with `-fsanitize=address` and the dylib is compiled with ASan (so, `_LIBCPP_INSTRUMENTED_WITH_ASAN` is defined). This ensures that the string annotations are only included when they are supported.

Some files are missing annotations checks, this commit adds those checks.

This commit adds a few test cases to check ASan annotations for SSO/no-SSO.

Resolved an issue with ASan annotations that was causing failure of `substr_rvalue` tests.

This commit fixes issues related to annotations and instrumentation, causing problems only with SSO annotations. First, it fixes an issue where `_LIBCPP_STRING_INTERNAL_MEMORY_ACCESS` doesn't work in `basic_string<_CharT, _Traits, _Allocator>::__move_assign(basic_string& __str, true_type)``. Second, it adds missing SSO annotations and refactors annotations around `__uninitialized_size_tag`. To reproduce the errors in this commit, change `_LIBCPP_SHORT_STRING_ANNOTATIONS_ALLOWED` to true. This flag will be changed to true (and probably deleted) soon.

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[ASan][libc++] std::basic_string annotations #72677

[ASan][libc++] std::basic_string annotations #72677

Commits on Dec 12, 2023