Fix string::replace under ASan (#3884)

Co-authored-by: Nicole Mazzuca <[email protected]> Co-authored-by: Stephan T. Lavavej <[email protected]>
microsoft · Jul 20, 2023 · 8a93121 · 8a93121
1 parent 34f86c5
commit 8a93121
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diff --git a/stl/inc/xstring b/stl/inc/xstring
@@ -3807,12 +3807,13 @@ public:
             // either we are shrinking, or the growth fits
             // may temporarily overflow; OK because size_type must be unsigned
             const auto _New_size = _Old_size + _Count - _Nx;
-            _ASAN_STRING_MODIFY(*this, _Old_size, _New_size);
+            _ASAN_STRING_REMOVE(*this);
             _Mypair._Myval2._Mysize = _New_size;
             _Elem* const _Old_ptr   = _Mypair._Myval2._Myptr();
             _Elem* const _Insert_at = _Old_ptr + _Off;
             _Traits::move(_Insert_at + _Count, _Insert_at + _Nx, _Old_size - _Nx - _Off + 1);
             _Traits::assign(_Insert_at, _Count, _Ch);
+            _ASAN_STRING_CREATE(*this);
             return *this;
         }
 

diff --git a/tests/std/tests/GH_002030_asan_annotate_string/test.cpp b/tests/std/tests/GH_002030_asan_annotate_string/test.cpp
@@ -1913,6 +1913,13 @@ void test_DevCom_10109507() {
     assert(s == "xyefbcd");
 }
 
+void test_gh_3883() {
+    // GH-3883 <string>: basic_string::replace fails under ASan when pos + count > size, and count2 < count
+    string t = "0123456789ABCDEF"; // large string
+    t.replace(0, 30, 7, 'A');
+    assert(t == "AAAAAAA");
+}
+
 int main() {
     run_allocator_matrix<char>();
 #ifdef __cpp_char8_t
@@ -1924,4 +1931,5 @@ int main() {
 
     test_DevCom_10116361();
     test_DevCom_10109507();
+    test_gh_3883();
 }