48 lines
1.6 KiB
C++
48 lines
1.6 KiB
C++
// Copyright 2018 The Crashpad Authors. All rights reserved.
|
|
//
|
|
// Licensed under the Apache License, Version 2.0 (the "License");
|
|
// you may not use this file except in compliance with the License.
|
|
// You may obtain a copy of the License at
|
|
//
|
|
// http://www.apache.org/licenses/LICENSE-2.0
|
|
//
|
|
// Unless required by applicable law or agreed to in writing, software
|
|
// distributed under the License is distributed on an "AS IS" BASIS,
|
|
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
// See the License for the specific language governing permissions and
|
|
// limitations under the License.
|
|
|
|
#include "test/scoped_guarded_page.h"
|
|
|
|
#include <sys/mman.h>
|
|
|
|
#include "base/check.h"
|
|
#include "base/memory/page_size.h"
|
|
|
|
namespace crashpad {
|
|
namespace test {
|
|
|
|
ScopedGuardedPage::ScopedGuardedPage() {
|
|
ptr_ = mmap(nullptr,
|
|
base::GetPageSize() * 2,
|
|
PROT_READ | PROT_WRITE,
|
|
MAP_PRIVATE | MAP_ANONYMOUS,
|
|
-1,
|
|
0);
|
|
PCHECK(ptr_ != MAP_FAILED) << "mmap";
|
|
|
|
// Simply mprotect()ing the guard page PROT_NONE does not make it inaccessible
|
|
// using ptrace() or /proc/$pid/mem so we munmap() the following page instead.
|
|
// Unfortunately, this means that the guarded page is not thread safe from
|
|
// other threads mapping a single page into the empty region.
|
|
char* second_page = static_cast<char*>(ptr_) + base::GetPageSize();
|
|
PCHECK(munmap(second_page, base::GetPageSize()) >= 0) << "munmap";
|
|
}
|
|
|
|
ScopedGuardedPage::~ScopedGuardedPage() {
|
|
PCHECK(munmap(ptr_, base::GetPageSize()) >= 0) << "munmap";
|
|
}
|
|
|
|
} // namespace test
|
|
} // namespace crashpad
|