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// Copyright 2018 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "base/win/scoped_handle_verifier.h"
#include <windows.h>
#include <stddef.h>
#include <unordered_map>
#include "base/debug/alias.h"
#include "base/debug/stack_trace.h"
#include "base/synchronization/lock_impl.h"
#include "base/win/base_win_buildflags.h"
#include "base/win/current_module.h"
extern "C" {
__declspec(dllexport) void* GetHandleVerifier();
void* GetHandleVerifier() {
return base::win::internal::ScopedHandleVerifier::Get();
}
} // extern C
namespace {
base::win::internal::ScopedHandleVerifier* g_active_verifier = nullptr;
using GetHandleVerifierFn = void* (*)();
using HandleMap =
std::unordered_map<HANDLE,
base::win::internal::ScopedHandleVerifierInfo,
base::win::internal::HandleHash>;
using NativeLock = base::internal::LockImpl;
NativeLock* GetLock() {
static auto* native_lock = new NativeLock();
return native_lock;
}
// Simple automatic locking using a native critical section so it supports
// recursive locking.
class AutoNativeLock {
public:
explicit AutoNativeLock(NativeLock& lock) : lock_(lock) { lock_.Lock(); }
~AutoNativeLock() { lock_.Unlock(); }
private:
NativeLock& lock_;
DISALLOW_COPY_AND_ASSIGN(AutoNativeLock);
};
} // namespace
namespace base {
namespace win {
namespace internal {
ScopedHandleVerifier::ScopedHandleVerifier(bool enabled)
: enabled_(enabled), lock_(GetLock()) {}
// static
ScopedHandleVerifier* ScopedHandleVerifier::Get() {
if (!g_active_verifier)
ScopedHandleVerifier::InstallVerifier();
return g_active_verifier;
}
bool CloseHandleWrapper(HANDLE handle) {
if (!::CloseHandle(handle))
// Making this DCHECK on non-Nighly as we are hitting this frequently,
// looks like we are closing handles twice somehow. See bug 1564899.
#if defined(NIGHTLY_BUILD)
CHECK(false); // CloseHandle failed.
#else
DCHECK(false); // CloseHandle failed.
#endif
return true;
}
// Assigns the g_active_verifier global within the GetLock() lock.
// If |existing_verifier| is non-null then |enabled| is ignored.
void ThreadSafeAssignOrCreateScopedHandleVerifier(
ScopedHandleVerifier* existing_verifier,
bool enabled) {
AutoNativeLock lock(*GetLock());
// Another thread in this module might be trying to assign the global
// verifier, so check that within the lock here.
if (g_active_verifier)
return;
g_active_verifier =
existing_verifier ? existing_verifier : new ScopedHandleVerifier(enabled);
}
// static
void ScopedHandleVerifier::InstallVerifier() {
#if BUILDFLAG(SINGLE_MODULE_MODE_HANDLE_VERIFIER)
// Component build has one Active Verifier per module.
ThreadSafeAssignOrCreateScopedHandleVerifier(nullptr, true);
#else
// If you are reading this, wondering why your process seems deadlocked, take
// a look at your DllMain code and remove things that should not be done
// there, like doing whatever gave you that nice windows handle you are trying
// to store in a ScopedHandle.
HMODULE main_module = ::GetModuleHandle(NULL);
GetHandleVerifierFn get_handle_verifier =
reinterpret_cast<GetHandleVerifierFn>(
::GetProcAddress(main_module, "GetHandleVerifier"));
// This should only happen if running in a DLL is linked with base but the
// hosting EXE is not. In this case, create an ScopedHandleVerifier for the
// current
// module but leave it disabled.
if (!get_handle_verifier) {
ThreadSafeAssignOrCreateScopedHandleVerifier(nullptr, false);
return;
}
// Check if in the main module.
if (get_handle_verifier == GetHandleVerifier) {
ThreadSafeAssignOrCreateScopedHandleVerifier(nullptr, true);
return;
}
ScopedHandleVerifier* main_module_verifier =
reinterpret_cast<ScopedHandleVerifier*>(get_handle_verifier());
// Main module should always on-demand create a verifier.
DCHECK(main_module_verifier);
ThreadSafeAssignOrCreateScopedHandleVerifier(main_module_verifier, false);
#endif
}
bool ScopedHandleVerifier::CloseHandle(HANDLE handle) {
if (!enabled_)
return CloseHandleWrapper(handle);
closing_.Set(true);
CloseHandleWrapper(handle);
closing_.Set(false);
return true;
}
// static
NativeLock* ScopedHandleVerifier::GetLock() {
return ::GetLock();
}
void ScopedHandleVerifier::StartTracking(HANDLE handle,
const void* owner,
const void* pc1,
const void* pc2) {
if (!enabled_)
return;
// Grab the thread id before the lock.
DWORD thread_id = GetCurrentThreadId();
AutoNativeLock lock(*lock_);
ScopedHandleVerifierInfo handle_info = {owner, pc1, pc2,
base::debug::StackTrace(), thread_id};
std::pair<HANDLE, ScopedHandleVerifierInfo> item(handle, handle_info);
std::pair<HandleMap::iterator, bool> result = map_.insert(item);
if (!result.second) {
ScopedHandleVerifierInfo other = result.first->second;
base::debug::Alias(&other);
auto creation_stack = creation_stack_;
base::debug::Alias(&creation_stack);
CHECK(false); // Attempt to start tracking already tracked handle.
}
}
void ScopedHandleVerifier::StopTracking(HANDLE handle,
const void* owner,
const void* pc1,
const void* pc2) {
if (!enabled_)
return;
AutoNativeLock lock(*lock_);
HandleMap::iterator i = map_.find(handle);
if (i == map_.end()) {
auto creation_stack = creation_stack_;
base::debug::Alias(&creation_stack);
CHECK(false); // Attempting to close an untracked handle.
}
ScopedHandleVerifierInfo other = i->second;
if (other.owner != owner) {
base::debug::Alias(&other);
auto creation_stack = creation_stack_;
base::debug::Alias(&creation_stack);
CHECK(false); // Attempting to close a handle not owned by opener.
}
map_.erase(i);
}
void ScopedHandleVerifier::Disable() {
enabled_ = false;
}
void ScopedHandleVerifier::OnHandleBeingClosed(HANDLE handle) {
if (!enabled_)
return;
if (closing_.Get())
return;
AutoNativeLock lock(*lock_);
HandleMap::iterator i = map_.find(handle);
if (i == map_.end())
return;
ScopedHandleVerifierInfo other = i->second;
base::debug::Alias(&other);
auto creation_stack = creation_stack_;
base::debug::Alias(&creation_stack);
CHECK(false); // CloseHandle called on tracked handle.
}
HMODULE ScopedHandleVerifier::GetModule() const {
return CURRENT_MODULE();
}
HMODULE GetHandleVerifierModuleForTesting() {
return g_active_verifier->GetModule();
}
} // namespace internal
} // namespace win
} // namespace base
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