134 lines
4.7 KiB
C++
134 lines
4.7 KiB
C++
// Copyright (c) 2011 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#include "base/synchronization/lock_impl.h"
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#include <string>
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#include "base/debug/activity_tracker.h"
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#include "base/logging.h"
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#include "base/posix/safe_strerror.h"
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#include "base/strings/stringprintf.h"
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#include "base/synchronization/lock.h"
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#include "base/synchronization/synchronization_buildflags.h"
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#include "build/build_config.h"
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namespace base {
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namespace internal {
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namespace {
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#if DCHECK_IS_ON()
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const char* AdditionalHintForSystemErrorCode(int error_code) {
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switch (error_code) {
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case EINVAL:
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return "Hint: This is often related to a use-after-free.";
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default:
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return "";
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}
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}
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#endif // DCHECK_IS_ON()
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std::string SystemErrorCodeToString(int error_code) {
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#if DCHECK_IS_ON()
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return base::safe_strerror(error_code) + ". " +
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AdditionalHintForSystemErrorCode(error_code);
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#else // DCHECK_IS_ON()
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return std::string();
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#endif // DCHECK_IS_ON()
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}
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} // namespace
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// Determines which platforms can consider using priority inheritance locks. Use
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// this define for platform code that may not compile if priority inheritance
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// locks aren't available. For this platform code,
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// PRIORITY_INHERITANCE_LOCKS_POSSIBLE() is a necessary but insufficient check.
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// Lock::PriorityInheritanceAvailable still must be checked as the code may
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// compile but the underlying platform still may not correctly support priority
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// inheritance locks.
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#if defined(OS_NACL) || defined(OS_ANDROID) || defined(OS_FUCHSIA)
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#define PRIORITY_INHERITANCE_LOCKS_POSSIBLE() 0
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#else
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#define PRIORITY_INHERITANCE_LOCKS_POSSIBLE() 1
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#endif
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LockImpl::LockImpl() {
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pthread_mutexattr_t mta;
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int rv = pthread_mutexattr_init(&mta);
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DCHECK_EQ(rv, 0) << ". " << SystemErrorCodeToString(rv);
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#if PRIORITY_INHERITANCE_LOCKS_POSSIBLE()
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if (PriorityInheritanceAvailable()) {
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rv = pthread_mutexattr_setprotocol(&mta, PTHREAD_PRIO_INHERIT);
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DCHECK_EQ(rv, 0) << ". " << SystemErrorCodeToString(rv);
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}
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#endif
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#ifndef NDEBUG
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// In debug, setup attributes for lock error checking.
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rv = pthread_mutexattr_settype(&mta, PTHREAD_MUTEX_ERRORCHECK);
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DCHECK_EQ(rv, 0) << ". " << SystemErrorCodeToString(rv);
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#endif
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rv = pthread_mutex_init(&native_handle_, &mta);
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DCHECK_EQ(rv, 0) << ". " << SystemErrorCodeToString(rv);
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rv = pthread_mutexattr_destroy(&mta);
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DCHECK_EQ(rv, 0) << ". " << SystemErrorCodeToString(rv);
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}
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LockImpl::~LockImpl() {
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int rv = pthread_mutex_destroy(&native_handle_);
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DCHECK_EQ(rv, 0) << ". " << SystemErrorCodeToString(rv);
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}
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bool LockImpl::Try() {
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int rv = pthread_mutex_trylock(&native_handle_);
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DCHECK(rv == 0 || rv == EBUSY) << ". " << SystemErrorCodeToString(rv);
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return rv == 0;
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}
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void LockImpl::Lock() {
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// The ScopedLockAcquireActivity below is relatively expensive and so its
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// actions can become significant due to the very large number of locks
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// that tend to be used throughout the build. To avoid this cost in the
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// vast majority of the calls, simply "try" the lock first and only do the
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// (tracked) blocking call if that fails. Since "try" itself is a system
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// call, and thus also somewhat expensive, don't bother with it unless
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// tracking is actually enabled.
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if (base::debug::GlobalActivityTracker::IsEnabled())
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if (Try())
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return;
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base::debug::ScopedLockAcquireActivity lock_activity(this);
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int rv = pthread_mutex_lock(&native_handle_);
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DCHECK_EQ(rv, 0) << ". " << SystemErrorCodeToString(rv);
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}
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// static
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bool LockImpl::PriorityInheritanceAvailable() {
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#if BUILDFLAG(ENABLE_MUTEX_PRIORITY_INHERITANCE)
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return true;
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#elif PRIORITY_INHERITANCE_LOCKS_POSSIBLE() && defined(OS_MACOSX)
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return true;
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#else
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// Security concerns prevent the use of priority inheritance mutexes on Linux.
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// * CVE-2010-0622 - Linux < 2.6.33-rc7, wake_futex_pi possible DoS.
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// https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2010-0622
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// * CVE-2012-6647 - Linux < 3.5.1, futex_wait_requeue_pi possible DoS.
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// https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2012-6647
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// * CVE-2014-3153 - Linux <= 3.14.5, futex_requeue, privilege escalation.
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// https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2014-3153
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//
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// If the above were all addressed, we still need a runtime check to deal with
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// the bug below.
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// * glibc Bug 14652: https://sourceware.org/bugzilla/show_bug.cgi?id=14652
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// Fixed in glibc 2.17.
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// Priority inheritance mutexes may deadlock with condition variables
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// during reacquisition of the mutex after the condition variable is
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// signalled.
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return false;
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#endif
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}
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} // namespace internal
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} // namespace base
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