[libcxx-commits] [libcxx] [libc++] Fix vector sanitization annotations on destruction (PR #121031)

[Dominic Chen via libcxx-commits]

https://github.com/ddcc updated https://github.com/llvm/llvm-project/pull/121031

>From 6efac0894a9ac0d3f8fc239a73d0b3da6971b53d Mon Sep 17 00:00:00 2001
From: Dominic Chen <ddchen at apple.com>
Date: Mon, 23 Dec 2024 21:50:55 -0800
Subject: [PATCH] [libc++] Fix vector sanitization annotations on destruction

In D144155/D136765, the asan annotations for std::vector were modified to unpoison freed backing memory on destruction, instead of leaving it
poisoned. However, calling `__clear()` instead of `clear()` skips informing the asan runtime of this decrease in the accessible container size, which
breaks the invariant that the value of `old_mid` should match the value of `new_mid` from the previous call to _sanitizer_annotate_contiguous_container(),
which can trip the sanity checks for the partial poison between [d1, d2) and the container redzone between [d2, c), if enabled. To fix this, ensure that
`clear()` is called instead, as is already done by `__vdeallocate()`.
---
 libcxx/include/__vector/vector.h | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/libcxx/include/__vector/vector.h b/libcxx/include/__vector/vector.h
index 6ba7ba7bcf724b..2ebacd324394c6 100644
--- a/libcxx/include/__vector/vector.h
+++ b/libcxx/include/__vector/vector.h
@@ -241,7 +241,7 @@ class _LIBCPP_TEMPLATE_VIS vector {
 
     _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void operator()() {
       if (__vec_.__begin_ != nullptr) {
-        __vec_.__clear();
+        __vec_.clear();
         __vec_.__annotate_delete();
         __alloc_traits::deallocate(__vec_.__alloc_, __vec_.__begin_, __vec_.capacity());
       }
@@ -520,7 +520,7 @@ class _LIBCPP_TEMPLATE_VIS vector {
 
   _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void clear() _NOEXCEPT {
     size_type __old_size = size();
-    __clear();
+    __base_destruct_at_end(this->__begin_);
     __annotate_shrink(__old_size);
   }
 
@@ -732,10 +732,6 @@ class _LIBCPP_TEMPLATE_VIS vector {
     ++__tx.__pos_;
   }
 
-  _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void __clear() _NOEXCEPT {
-    __base_destruct_at_end(this->__begin_);
-  }
-
   _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void __base_destruct_at_end(pointer __new_last) _NOEXCEPT {
     pointer __soon_to_be_end = this->__end_;
     while (__new_last != __soon_to_be_end)
@@ -759,7 +755,7 @@ class _LIBCPP_TEMPLATE_VIS vector {
 
   _LIBCPP_CONSTEXPR_SINCE_CXX20 _LIBCPP_HIDE_FROM_ABI void __copy_assign_alloc(const vector& __c, true_type) {
     if (this->__alloc_ != __c.__alloc_) {
-      __clear();
+      clear();
       __annotate_delete();
       __alloc_traits::deallocate(this->__alloc_, this->__begin_, capacity());
       this->__begin_ = this->__end_ = this->__cap_ = nullptr;