[PATCH 2/2] test: py: LD_PRELOAD the C++ standard library when using ASan

[Kieran Bingham]

Quoting Laurent Pinchart (2024-11-05 01:49:49)
> When the ASan runtime is linked using --as-needed, its dependency on the
> C++ standard library is stripped. This results to a failure to properly
> handled exceptions when a C++ dynamically loaded .so is used, as in the
> Python unit tests that load the libcamera Python module:
> 
> AddressSanitizer: CHECK failed: asan_interceptors.cpp:335 "((__interception::real___cxa_throw)) != (0)" (0x0, 0x0) (tid=32679)
>     #0 0x7fa2f32e6c19 in CheckUnwind /var/tmp/portage/sys-devel/gcc-13.3.1_p20241025/work/gcc-13-20241025/libsanitizer/asan/asan_rtl.cpp:69
>     #1 0x7fa2f330c9fd in __sanitizer::CheckFailed(char const*, int, char const*, unsigned long long, unsigned long long) /var/tmp/portage/sys-devel/gcc-13.3.1_p20241025/work/gcc-13-20241025/libsanitizer/sanitizer_common/sanitizer_termination.cpp:86
>     #2 0x7fa2f3247824 in __interceptor___cxa_throw /var/tmp/portage/sys-devel/gcc-13.3.1_p20241025/work/gcc-13-20241025/libsanitizer/asan/asan_interceptors.cpp:335
>     #3 0x7fa2f3247824 in __interceptor___cxa_throw /var/tmp/portage/sys-devel/gcc-13.3.1_p20241025/work/gcc-13-20241025/libsanitizer/asan/asan_interceptors.cpp:334
>     #4 0x7fa2efb6da8b in operator() ../../src/py/libcamera/py_main.cpp:157
> [...]
> 
> The issue has been reported in [1] and so far remains unfixed. Work
> around it by preloading the C++ standard library.
> 
> [1] https://github.com/google/sanitizers/issues/934
> 
> Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> ---
>  meson.build         | 3 +++
>  test/py/meson.build | 6 ++++++
>  2 files changed, 9 insertions(+)
> 
> diff --git a/meson.build b/meson.build
> index 63e45465da9c..e3052260f13e 100644
> --- a/meson.build
> +++ b/meson.build
> @@ -112,6 +112,8 @@ common_arguments = [
>  c_arguments = []
>  cpp_arguments = []
>  
> +cxx_stdlib = 'libstdc++'
> +
>  if cc.get_id() == 'clang'
>      if cc.version().version_compare('<9')
>          error('clang version is too old, libcamera requires 9.0 or newer')
> @@ -137,6 +139,7 @@ if cc.get_id() == 'clang'
>          cpp_arguments += [
>              '-stdlib=libc++',
>          ]
> +        cxx_stdlib = 'libc++'
>      endif
>  
>      cpp_arguments += [
> diff --git a/test/py/meson.build b/test/py/meson.build
> index 481bb481c110..b922e8578c29 100644
> --- a/test/py/meson.build
> +++ b/test/py/meson.build
> @@ -24,6 +24,12 @@ py_env.append('PYTHONPATH', pypathdir)
>  if asan_enabled
>      py_env.append('LD_PRELOAD', asan_runtime)
>  
> +    # Preload the C++ standard library to work around a bug in ASan when
> +    # dynamically loading C++ .so modules.
> +    stdlib = run_command(cxx, '-print-file-name=' + cxx_stdlib + '.so',
> +                         check : true).stdout().strip()
> +    py_env.append('LD_PRELOAD', stdlib)
> +

I assume it is, but have never used LD_PRELOAD this way - is it safe to
have multiple instances of the environment variable?


Does this make a space separated list? Or does it make
LD_PRELOAD=file1.so LD_PRELOAD=file2.so appear in the env?

I presume whatever it does it works as you'll have used it ...

so presumptively:


Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>

But I'm interested to know which form is used by meson when appending
the same variable to an environment for future use cases.

--
Kieran


>      # Disable leak detection as the Python interpreter is full of leaks.
>      py_env.append('ASAN_OPTIONS', 'detect_leaks=0')
>  endif
> -- 
> Regards,
> 
> Laurent Pinchart
>