[ASan] Allow new/delete replacement by making interceptors weak

[hctim]

Summary

ASan declares these functions as strongly-defined, which results in
'duplicate symbol' errors when trying to replace them in user code when
linking the runtimes statically.

[eugenis]

Add it to CXX_OPERATOR_ATTRIBUTE, on non-mac non-windows?

[hctim]

In D100220#2680431, @eugenis wrote:

Add it to CXX_OPERATOR_ATTRIBUTE, on non-mac non-windows?

Done.

[hctim]

wrong diffbase messed up phabricator rendering

[eugenis]

LGTM

[morehouse]

compiler-rt/test/asan/TestCases/replaceable_new_delete.cpp

2

This test is failing on Windows: https://lab.llvm.org/buildbot/#/builders/127/builds/9062

[hctim]

compiler-rt/test/asan/TestCases/replaceable_new_delete.cpp

2

Thanks, submitted 15689f3af018c420403bb0fd0df0aa5f79796b94 to disable this test on windows. I think the issue can be permanently solved using some of the SANITIZER_INTERFACE_WEAK_DEF(ReturnType, Name, ...) macros in compiler-rt, but I don't have a Windows machine to test on.

The test disablement on Windows is fine, it just means that Windows isn't getting the new replaceable behaviour.

compiler-rt/lib/asan/asan_new_delete.cpp

 // On OS X it's not enough to just provide our own 'operator new' and
 // 'operator delete' implementations, because they're going to be in the
 // runtime dylib, and the main executable will depend on both the runtime
 // dylib and libstdc++, each of those'll have its implementation of new and
 // delete.
 // To make sure that C++ allocation/deallocation operators are overridden on
 // OS X we need to intercept them using their mangled names.
 #if !SANITIZER_MAC
-CXX_OPERATOR_ATTRIBUTE
+CXX_OPERATOR_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
 void *operator new(size_t size)
 { OPERATOR_NEW_BODY(FROM_NEW, false /*nothrow*/); }
-CXX_OPERATOR_ATTRIBUTE
+CXX_OPERATOR_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
 void *operator new[](size_t size)
 { OPERATOR_NEW_BODY(FROM_NEW_BR, false /*nothrow*/); }
-CXX_OPERATOR_ATTRIBUTE
+CXX_OPERATOR_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
 void *operator new(size_t size, std::nothrow_t const&)
 { OPERATOR_NEW_BODY(FROM_NEW, true /*nothrow*/); }
-CXX_OPERATOR_ATTRIBUTE
+CXX_OPERATOR_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
 void *operator new[](size_t size, std::nothrow_t const&)
 { OPERATOR_NEW_BODY(FROM_NEW_BR, true /*nothrow*/); }
-CXX_OPERATOR_ATTRIBUTE
+CXX_OPERATOR_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
 void *operator new(size_t size, std::align_val_t align)
 { OPERATOR_NEW_BODY_ALIGN(FROM_NEW, false /*nothrow*/); }
-CXX_OPERATOR_ATTRIBUTE
+CXX_OPERATOR_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
 void *operator new[](size_t size, std::align_val_t align)
 { OPERATOR_NEW_BODY_ALIGN(FROM_NEW_BR, false /*nothrow*/); }
-CXX_OPERATOR_ATTRIBUTE
+CXX_OPERATOR_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
 void *operator new(size_t size, std::align_val_t align, std::nothrow_t const&)
 { OPERATOR_NEW_BODY_ALIGN(FROM_NEW, true /*nothrow*/); }
-CXX_OPERATOR_ATTRIBUTE
+CXX_OPERATOR_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
 void *operator new[](size_t size, std::align_val_t align, std::nothrow_t const&)
 { OPERATOR_NEW_BODY_ALIGN(FROM_NEW_BR, true /*nothrow*/); }
 
 #else  // SANITIZER_MAC
 INTERCEPTOR(void *, _Znwm, size_t size) {
   OPERATOR_NEW_BODY(FROM_NEW, false /*nothrow*/);
 }
 INTERCEPTOR(void *, _Znam, size_t size) {
#define OPERATOR_DELETE_BODY_ALIGN(type) \
   asan_delete(ptr, 0, static_cast<uptr>(align), &stack, type);
 
 #define OPERATOR_DELETE_BODY_SIZE_ALIGN(type) \
   if (IS_FROM_LOCAL_POOL(ptr)) return;\
   GET_STACK_TRACE_FREE;\
   asan_delete(ptr, size, static_cast<uptr>(align), &stack, type);
 
 #if !SANITIZER_MAC
-CXX_OPERATOR_ATTRIBUTE
+CXX_OPERATOR_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
 void operator delete(void *ptr) NOEXCEPT
 { OPERATOR_DELETE_BODY(FROM_NEW); }
-CXX_OPERATOR_ATTRIBUTE
+CXX_OPERATOR_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
 void operator delete[](void *ptr) NOEXCEPT
 { OPERATOR_DELETE_BODY(FROM_NEW_BR); }
-CXX_OPERATOR_ATTRIBUTE
+CXX_OPERATOR_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
 void operator delete(void *ptr, std::nothrow_t const&)
 { OPERATOR_DELETE_BODY(FROM_NEW); }
-CXX_OPERATOR_ATTRIBUTE
+CXX_OPERATOR_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
 void operator delete[](void *ptr, std::nothrow_t const&)
 { OPERATOR_DELETE_BODY(FROM_NEW_BR); }
-CXX_OPERATOR_ATTRIBUTE
+CXX_OPERATOR_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
 void operator delete(void *ptr, size_t size) NOEXCEPT
 { OPERATOR_DELETE_BODY_SIZE(FROM_NEW); }
-CXX_OPERATOR_ATTRIBUTE
+CXX_OPERATOR_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
 void operator delete[](void *ptr, size_t size) NOEXCEPT
 { OPERATOR_DELETE_BODY_SIZE(FROM_NEW_BR); }
-CXX_OPERATOR_ATTRIBUTE
+CXX_OPERATOR_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
 void operator delete(void *ptr, std::align_val_t align) NOEXCEPT
 { OPERATOR_DELETE_BODY_ALIGN(FROM_NEW); }
-CXX_OPERATOR_ATTRIBUTE
+CXX_OPERATOR_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
 void operator delete[](void *ptr, std::align_val_t align) NOEXCEPT
 { OPERATOR_DELETE_BODY_ALIGN(FROM_NEW_BR); }
-CXX_OPERATOR_ATTRIBUTE
+CXX_OPERATOR_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
 void operator delete(void *ptr, std::align_val_t align, std::nothrow_t const&)
 { OPERATOR_DELETE_BODY_ALIGN(FROM_NEW); }
-CXX_OPERATOR_ATTRIBUTE
+CXX_OPERATOR_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
 void operator delete[](void *ptr, std::align_val_t align, std::nothrow_t const&)
 { OPERATOR_DELETE_BODY_ALIGN(FROM_NEW_BR); }
-CXX_OPERATOR_ATTRIBUTE
+CXX_OPERATOR_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
 void operator delete(void *ptr, size_t size, std::align_val_t align) NOEXCEPT
 { OPERATOR_DELETE_BODY_SIZE_ALIGN(FROM_NEW); }
-CXX_OPERATOR_ATTRIBUTE
+CXX_OPERATOR_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
 void operator delete[](void *ptr, size_t size, std::align_val_t align) NOEXCEPT
 { OPERATOR_DELETE_BODY_SIZE_ALIGN(FROM_NEW_BR); }
 
 #else  // SANITIZER_MAC
 INTERCEPTOR(void, _ZdlPv, void *ptr)
 { OPERATOR_DELETE_BODY(FROM_NEW); }
 INTERCEPTOR(void, _ZdaPv, void *ptr)
 { OPERATOR_DELETE_BODY(FROM_NEW_BR); }
 INTERCEPTOR(void, _ZdlPvRKSt9nothrow_t, void *ptr, std::nothrow_t const&)
 { OPERATOR_DELETE_BODY(FROM_NEW); }
 INTERCEPTOR(void, _ZdaPvRKSt9nothrow_t, void *ptr, std::nothrow_t const&)
 { OPERATOR_DELETE_BODY(FROM_NEW_BR); }
 #endif  // !SANITIZER_MAC

compiler-rt/test/asan/TestCases/replaceable_new_delete.cpp

+// Ensure that operator new/delete are still replaceable.
+
+// RUN: %clangxx %s -o %t -fsanitize=address -shared-libsan && not %run %t 2>&1 | FileCheck %s
+// RUN: %clangxx %s -o %t -fsanitize=address -static-libsan && not %run %t 2>&1 | FileCheck %s
+
+#include <cstdio>
+#include <cstdlib>
+#include <new>
+
+void *operator new[](size_t size) {
+  fprintf(stderr, "replaced new\n");
+  return malloc(size);
+}
+
+void operator delete[](void *ptr) noexcept {
+  fprintf(stderr, "replaced delete\n");
+  return free(ptr);
+}
+
+int main(int argc, char **argv) {
+  // CHECK: replaced new
+  char *x = new char[5];
+  // CHECK: replaced delete
+  delete[] x;
+  // CHECK: ERROR: AddressSanitizer
+  *x = 13;
+  return 0;
+}