[all-commits] [llvm/llvm-project] 0be4c6: [sanitizer_common] Add experimental flag to tweak ...

[Thurston Dang via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 0be4c6b9483594494051e8f1f67afc2b516270ca
      https://github.com/llvm/llvm-project/commit/0be4c6b9483594494051e8f1f67afc2b516270ca
  Author: Thurston Dang <thurston.dang at gmail.com>
  Date:   2023-11-09 (Thu, 09 Nov 2023)

  Changed paths:
    M compiler-rt/lib/sanitizer_common/CMakeLists.txt
    M compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc
    A compiler-rt/lib/sanitizer_common/sanitizer_dl.cpp
    A compiler-rt/lib/sanitizer_common/sanitizer_dl.h
    M compiler-rt/lib/sanitizer_common/sanitizer_flags.inc
    A compiler-rt/test/sanitizer_common/TestCases/Linux/replace_dlopen_main_program_test.cpp
    M llvm/utils/gn/secondary/compiler-rt/lib/sanitizer_common/BUILD.gn

  Log Message:
  -----------
  [sanitizer_common] Add experimental flag to tweak dlopen(<main program>) (#71715)

This introduces an experimental flag 'test_only_replace_dlopen_main_program'. When enabled, this will replace dlopen(main program,...) with dlopen(NULL,...), which is the correct way to get a handle to the main program.

This can be useful when ASan is statically linked, since dladdr((void*)pthread_join) or similar will return the path to the main program.

Note that dlopen(main program,...) never ends well:
- PIE in recent glibc versions (glibc bugzilla 24323), or non-PIE: return an error
- PIE in current GRTE and older glibc: attempt to load the main program again, leading to reinitializing ASan and failing to remap the shadow memory.

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Co-authored-by: Thurston Dang <thurston at google.com>