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Fix crash on shutdown with PDF viewer and multi-threaded message loop (fixes issue #2709, see issue #2622) 

Requests from the PDF viewer are not associated with a CefBrowser. Consequently,
the InterceptedRequestHandler for those requests will register as an observer of
CefContext destruction. When the browser is closed the InterceptedRequestHandler
is destroyed and an async task is posted to remove/delete the observer on the UI
thread. If CefShutdown is then called the task may execute after shutdown has
started, in which case CONTEXT_STATE_VALID() will return false. We still need to
remove the observer in this case to avoid a use-after-free in
FinishShutdownOnUIThread.
This commit is contained in:
Marshall Greenblatt 2019-07-23 15:10:45 -04:00
parent a697464a33
commit e57acace0b
1 changed files with 56 additions and 31 deletions
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85
libcef/browser/net_service/resource_request_handler_wrapper.cc
View File

@ -166,7 +166,32 @@ class InterceptedRequestHandlerWrapper : public InterceptedRequestHandler {
class DestructionObserver : public CefBrowserHostImpl::Observer,
public CefContext::Observer {
public:
DestructionObserver() = default;
explicit DestructionObserver(CefBrowserHostImpl* browser) {
if (browser) {
browser_info_ = browser->browser_info();
browser->AddObserver(this);
} else {
CefContext::Get()->AddObserver(this);
}
}
virtual ~DestructionObserver() {
CEF_REQUIRE_UIT();
if (!registered_)
return;
// Verify that the browser or context still exists before attempting to
// remove the observer.
if (browser_info_) {
auto browser = browser_info_->browser();
if (browser)
browser->RemoveObserver(this);
} else if (CefContext::Get()) {
// Network requests may be torn down during shutdown, so we can't check
// CONTEXT_STATE_VALID() here.
CefContext::Get()->RemoveObserver(this);
}
}
void SetWrapper(base::WeakPtr<InterceptedRequestHandlerWrapper> wrapper) {
CEF_REQUIRE_IOT();
@ -176,23 +201,31 @@ class InterceptedRequestHandlerWrapper : public InterceptedRequestHandler {
void OnBrowserDestroyed(CefBrowserHostImpl* browser) override {
CEF_REQUIRE_UIT();
browser->RemoveObserver(this);
registered_ = false;
browser_info_ = nullptr;
NotifyOnDestroyed();
}
void OnContextDestroyed() override {
CEF_REQUIRE_UIT();
CefContext::Get()->RemoveObserver(this);
registered_ = false;
NotifyOnDestroyed();
}
private:
void NotifyOnDestroyed() {
// It's not safe to test the WeakPtr on the UI thread, so we'll just post
// a task which will be ignored if the WeakPtr is invalid.
CEF_POST_TASK(CEF_IOT, base::BindOnce(
&InterceptedRequestHandlerWrapper::OnDestroyed,
if (wrapper_.MaybeValid()) {
// This will be a no-op if the WeakPtr is invalid.
CEF_POST_TASK(
CEF_IOT,
base::BindOnce(&InterceptedRequestHandlerWrapper::OnDestroyed,
wrapper_));
}
}
scoped_refptr<CefBrowserInfo> browser_info_;
bool registered_ = true;
base::WeakPtr<InterceptedRequestHandlerWrapper> wrapper_;
DISALLOW_COPY_AND_ASSIGN(DestructionObserver);
@ -211,25 +244,7 @@ class InterceptedRequestHandlerWrapper : public InterceptedRequestHandler {
// InterceptedRequestHandlerWrapper::SetInitialized().
destruction_observer_->SetWrapper(nullptr);
}
CEF_POST_TASK(
CEF_UIT,
base::BindOnce(&InitState::RemoveDestructionObserverOnUIThread,
browser_ ? browser_->browser_info() : nullptr,
std::move(destruction_observer_)));
}
}
static void RemoveDestructionObserverOnUIThread(
scoped_refptr<CefBrowserInfo> browser_info,
std::unique_ptr<DestructionObserver> observer) {
// Verify that the browser or context is still valid before attempting to
// remove the observer.
if (browser_info) {
auto browser = browser_info->browser();
if (browser)
browser->RemoveObserver(observer.get());
} else if (CONTEXT_STATE_VALID()) {
CefContext::Get()->RemoveObserver(observer.get());
DeleteDestructionObserver();
}
}
@ -253,15 +268,12 @@ class InterceptedRequestHandlerWrapper : public InterceptedRequestHandler {
// that we can stop accepting new requests and cancel pending/in-progress
// requests in a timely manner (e.g. before we start asserting about
// leaked objects during CEF shutdown).
destruction_observer_.reset(new DestructionObserver());
destruction_observer_.reset(new DestructionObserver(browser.get()));
if (browser) {
// These references will be released in OnDestroyed().
browser_ = browser;
frame_ = frame;
browser->AddObserver(destruction_observer_.get());
} else {
CefContext::Get()->AddObserver(destruction_observer_.get());
}
render_process_id_ = render_process_id;
@ -279,6 +291,17 @@ class InterceptedRequestHandlerWrapper : public InterceptedRequestHandler {
DCHECK(!user_agent_.empty());
}
void DeleteDestructionObserver() {
DCHECK(destruction_observer_);
CEF_POST_TASK(
CEF_UIT,
base::BindOnce(&InitState::DeleteDestructionObserverOnUIThread,
std::move(destruction_observer_)));
}
static void DeleteDestructionObserverOnUIThread(
std::unique_ptr<DestructionObserver> observer) {}
// Only accessed on the UI thread.
content::BrowserContext* browser_context_ = nullptr;
@ -1071,8 +1094,7 @@ class InterceptedRequestHandlerWrapper : public InterceptedRequestHandler {
CEF_REQUIRE_IOT();
DCHECK(init_state_);
DCHECK(init_state_->destruction_observer_);
init_state_->destruction_observer_.reset();
init_state_->DeleteDestructionObserver();
// Stop accepting new requests.
shutting_down_ = true;
@ -1207,6 +1229,7 @@ void InitOnUIThread(
}
#endif
// May return nullptr for requests originating from guest views.
browserPtr = CefBrowserHostImpl::GetBrowserForHost(frame);
if (browserPtr) {
framePtr = browserPtr->GetFrameForHost(frame);
@ -1253,6 +1276,8 @@ std::unique_ptr<InterceptedRequestHandler> CreateInterceptedRequestHandler(
if (frame) {
render_frame_id = frame->GetRoutingID();
frame_tree_node_id = frame->GetFrameTreeNodeId();
// May return nullptr for requests originating from guest views.
browserPtr = CefBrowserHostImpl::GetBrowserForHost(frame);
if (browserPtr) {
framePtr = browserPtr->GetFrameForHost(frame);