[libcxx-commits] [PATCH] D146214: [ASan][libc++] Annotating std::basic_string with all allocators

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This patch is part of our efforts to support container annotations with (almost) every allocator.
Annotating `std::basic_string` with default allocator is implemented in D132769 <https://reviews.llvm.org/D132769>.

In revision D132522 <https://reviews.llvm.org/D132522>, support for non-aligned memory buffers (sharing first/last granule with other objects) was added, therefore the check for standard allocator is not necessary.
This patch removes the check in std::basic_string annotation member function (__annotate_contiguous_container) to support different allocators and also includes changes from D145628 <https://reviews.llvm.org/D145628>, creating an easy way to turn off annotations for a specific allocator.

The motivation for a 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.

If you have any questions, please email:

- advenam.tacet at trailofbits.com
- disconnect3d at trailofbits.com


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D146214

Files:
  libcxx/include/string
  libcxx/test/libcxx/containers/strings/no_asan.pass.cpp
  libcxx/test/support/asan_testing.h

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