xref: /aosp_15_r20/bionic/tests/stack_protector_test_helper.cpp (revision 8d67ca893c1523eb926b9080dbe4e2ffd2a27ba1)
1  /*
2   * Copyright (C) 2012 The Android Open Source Project
3   *
4   * Licensed under the Apache License, Version 2.0 (the "License");
5   * you may not use this file except in compliance with the License.
6   * You may obtain a copy of the License at
7   *
8   *      http://www.apache.org/licenses/LICENSE-2.0
9   *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   * See the License for the specific language governing permissions and
14   * limitations under the License.
15   */
16  
17  // Deliberately overwrite the stack canary.
modify_stack_protector_test()18  __attribute__((noinline, optnone)) void modify_stack_protector_test() {
19    // We can't use memset here because it's fortified, and we want to test
20    // the line of defense *after* that.
21    // We can't make a constant change, since the existing byte might already have
22    // had that value.
23    char* p = reinterpret_cast<char*>(&p + 1);
24    *p = ~*p;
25  }
26