Fix null pointer dereference in weak_ref::get() #1232
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This happens to not cause any issues with MSVC, but does crash with MinGW ABI when built with optimizations, because a cast in `winrt::get_self` would adjust the (null) pointer by an offset due to the different vtable layout, which ends up escaping null checks.
kennykerr
approved these changes
Nov 21, 2022
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There was a null pointer dereference bug in
weak_ref::get(). This happens to not cause any issues with MSVC, but does crash with MinGW ABI when built with optimizations, because a cast inwinrt::get_selfwould adjust the (null) pointer by an offset due to the different vtable layout, which ends up escaping null checks.I didn't notice this earlier because all my tests happen to be unoptimized Debug builds. I tracked down this bug with the help of UBSan.
Because of this, I have also enabled Release build checks for llvm-mingw, and enabled ASan+UBSan for the tests in Debug builds.