Bug 293591 – com.apple.WebKit.WebContent crash at com.apple.WebCore: WebCore::preferredExtensionForImageType

• Status: RESOLVED
• Resolution: FIXED
• Component: Images

[David Kilzer (:ddkilzer)]

com.apple.WebKit.WebContent crash at com.apple.WebCore:  WebCore::preferredExtensionForImageType due to release assertion.

In Bug 256867, a release assert was added to verify that the value of `UTTypeCopyPreferredTagWithClass()` matched the value of `+[UTType typeWithIdentifier:]`, but in all the cases where we crash, the `UTType` method returns a valid file extension while `UTTypeCopyPreferredTagWithClass()` returned a null/empty string, so we can just switch to using the `UTType` method.

```
Thread 0 Crashed::   Dispatch queue: com.apple.main-thread
0   com.apple.JavaScriptCore      	       0x10834f77c WTFCrashWithInfoImpl(int, char const*, char const*, int, unsigned long long, unsigned long long, unsigned long long, unsigned long long, unsigned long long, unsigned long long)
1   com.apple.WebCore             	       0x119c5c818 WebCore::preferredExtensionForImageType(WTF::String const&)
2   com.apple.WebCore             	       0x11ae6a0a0 WebCore::ImageDecoderCG::filenameExtension() const
3   com.apple.WebCore             	       0x11ad5ec18 WTF::String WebCore::BitmapImageDescriptor::imageMetadata<WTF::String>(WTF::String&, WTF::String const&, WebCore::BitmapImageDescriptor::CachedFlag, WTF::String (WebCore::ImageDecoder::*)() const) const
4   com.apple.WebCore             	       0x11ad5eccc WebCore::BitmapImageDescriptor::filenameExtension() const
5   com.apple.WebKit              	       0x10b311884 WebKit::WebDragClient::declareAndWriteDragImage(WTF::String const&, WebCore::Element&, WTF::URL const&, WTF::String const&, WebCore::LocalFrame*)
6   com.apple.WebCore             	       0x11ab4fc90 WebCore::DragController::startDrag(WebCore::LocalFrame&, WebCore::DragState const&, WTF::OptionSet<WebCore::DragOperation>, WebCore::PlatformMouseEvent const&, WebCore::IntPoint const&, WebCore::HasNonDefaultPasteboardData)
7   com.apple.WebCore             	       0x11ab60324 WebCore::EventHandler::handleDrag(WebCore::MouseEventWithHitTestResults const&, WebCore::CheckDragHysteresis)
8   com.apple.WebCore             	       0x11ab5f774 WebCore::EventHandler::handleMouseDraggedEvent(WebCore::MouseEventWithHitTestResults const&, WebCore::CheckDragHysteresis)
9   com.apple.WebCore             	       0x11ab66d44 WebCore::EventHandler::handleMouseMoveEvent(WebCore::PlatformMouseEvent const&, WebCore::HitTestResult*, bool)
10  com.apple.WebCore             	       0x11ab6621c WebCore::EventHandler::mouseMoved(WebCore::PlatformMouseEvent const&)
11  com.apple.WebKit              	       0x10b6faf84 WebKit::WebFrame::handleMouseEvent(WebKit::WebMouseEvent const&)
12  com.apple.WebKit              	       0x10b70c10c WebKit::WebPage::mouseEvent(WebCore::ProcessQualified<WTF::ObjectIdentifierGeneric<WebCore::FrameIdentifierType, WTF::ObjectIdentifierMainThreadAccessTraits<unsigned long long>, unsigned long long>>, WebKit::WebMouseEvent const&, std::__1::optional<WTF::Vector<WebKit::SandboxExtensionHandle, 0ul, WTF::CrashOnOverflow, 16ul, WTF::FastMalloc>>&&)
13  com.apple.WebKit              	       0x10af3ce50 void IPC::handleMessage<Messages::WebPage::MouseEvent, IPC::Connection, WebKit::WebPage, WebKit::WebPage, void (WebCore::ProcessQualified<WTF::ObjectIdentifierGeneric<WebCore::FrameIdentifierType, WTF::ObjectIdentifierMainThreadAccessTraits<unsigned long long>, unsigned long long>>, WebKit::WebMouseEvent const&, std::__1::optional<WTF::Vector<WebKit::SandboxExtensionHandle, 0ul, WTF::CrashOnOverflow, 16ul, WTF::FastMalloc>>&&)>(IPC::Connection&, IPC::Decoder&, WebKit::WebPage*, void (WebKit::WebPage::*)(WebCore::ProcessQualified<WTF::ObjectIdentifierGeneric<WebCore::FrameIdentifierType, WTF::ObjectIdentifierMainThreadAccessTraits<unsigned long long>, unsigned long long>>, WebKit::WebMouseEvent const&, std::__1::optional<WTF::Vector<WebKit::SandboxExtensionHandle, 0ul, WTF::CrashOnOverflow, 16ul, WTF::FastMalloc>>&&))
14  com.apple.WebKit              	       0x10af395dc WebKit::WebPage::didReceiveMessage(IPC::Connection&, IPC::Decoder&)
15  com.apple.WebKit              	       0x10b93ce48 IPC::MessageReceiverMap::dispatchMessage(IPC::Connection&, IPC::Decoder&)
16  com.apple.WebKit              	       0x10b258ddc WebKit::AuxiliaryProcess::dispatchMessage(IPC::Connection&, IPC::Decoder&)
17  com.apple.WebKit              	       0x10ae5639c WebKit::AuxiliaryProcess::didReceiveMessage(IPC::Connection&, IPC::Decoder&)
18  com.apple.WebKit              	       0x10b937550 IPC::Connection::dispatchMessage(WTF::UniqueRef<IPC::Decoder>)
19  com.apple.WebKit              	       0x10b937700 IPC::Connection::dispatchOneIncomingMessage()
20  com.apple.JavaScriptCore      	       0x1083a1c04 WTF::RunLoop::performWork()
[...]
```

<rdar://132707082>

[David Kilzer (:ddkilzer)]

Pull request: https://github.com/WebKit/WebKit/pull/45921

[EWS]

Committed 295449@main (3f5ad67c9783): <https://commits.webkit.org/295449@main>

Reviewed commits have been landed. Closing PR #45921 and removing active labels.