[libcxx-commits] [PATCH] D96063: [🍒]Disable CFI in __get_elem to allow casting a pointer to uninitialized memory

Louis Dionne via Phabricator via libcxx-commits libcxx-commits at lists.llvm.org
Thu Feb 4 10:38:04 PST 2021

ldionne created this revision.
ldionne added a reviewer: tstellar.
Herald added a subscriber: jkorous.
ldionne requested review of this revision.
Herald added a project: libc++.
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Herald added a reviewer: libc++.

Fixes usage of shared_ptr with CFI enabled, which is llvm.org/pr48993.

(cherry pick of commit bab74864168bb5e28ecbc0294fe1095d8da7f569 <https://reviews.llvm.org/rGbab74864168bb5e28ecbc0294fe1095d8da7f569>)

  rG LLVM Github Monorepo



Index: libcxx/include/memory
--- libcxx/include/memory
+++ libcxx/include/memory
@@ -2647,7 +2647,7 @@
             _Alloc *__alloc = reinterpret_cast<_Alloc*>(__first);
             return __alloc;
-        _Tp* __get_elem() _NOEXCEPT {
+        _LIBCPP_NO_CFI _Tp* __get_elem() _NOEXCEPT {
             _CompressedPair *__as_pair = reinterpret_cast<_CompressedPair*>(__blob_);
             typename _CompressedPair::_Base2* __second = _CompressedPair::__get_second_base(__as_pair);
             _Tp *__elem = reinterpret_cast<_Tp*>(__second);

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