Bug 159328 – [iOS] Possible null Range dereference under computeAutocorrectionContext()

• Component: HTML Editing
• Status: RESOLVED FIXED

[Chris Dumez]

Possible null Range dereference under computeAutocorrectionContext():
Exception Type:  EXC_BAD_ACCESS (SIGSEGV)
Exception Subtype: KERN_INVALID_ADDRESS at 0x0000000000000018
Triggered by Thread:  0

Filtered syslog:
None found

Thread 0 name:  Dispatch queue: com.apple.main-thread
Thread 0 Crashed:
0   WebKit                        	0x000000018bf2130c WebCore::RangeBoundaryPoint::toPosition() const + 24 (RangeBoundaryPoint.h:93)
1   WebKit                        	0x000000018bf1ba5c WebKit::computeAutocorrectionContext(WebCore::Frame&, WTF::String&, WTF::String&, WTF::String&, WTF::String&, unsigned long long&, unsigned long long&) + 460 (Range.h:105)
2   WebKit                        	0x000000018bf1ba5c WebKit::computeAutocorrectionContext(WebCore::Frame&, WTF::String&, WTF::String&, WTF::String&, WTF::String&, unsigned long long&, unsigned long long&) + 460 (Range.h:105)
3   WebKit                        	0x000000018bf2a170 void IPC::handleMessage<Messages::WebPage::GetAutocorrectionContext, WebKit::WebPage, void (WebKit::WebPage::*)(WTF::String&, WTF::String&, WTF::String&, WTF::String&, unsigned long long&, unsigned long long&)>(IPC::MessageDecoder&, IPC::MessageEncoder&, WebKit::WebPage*, void (WebKit::WebPage::*)(WTF::String&, WTF::String&, WTF::String&, WTF::String&, unsigned long long&, unsigned long long&)) + 88 (HandleMessage.h:30)
4   WebKit                        	0x000000018be0f074 IPC::MessageReceiverMap::dispatchSyncMessage(IPC::Connection&, IPC::MessageDecoder&, std::__1::unique_ptr<IPC::MessageEncoder, std::__1::default_delete<IPC::MessageEncoder> >&) + 128 (MessageReceiverMap.cpp:119)
5   WebKit                        	0x000000018bf7c6d8 WebKit::WebProcess::didReceiveSyncMessage(IPC::Connection&, IPC::MessageDecoder&, std::__1::unique_ptr<IPC::MessageEncoder, std::__1::default_delete<IPC::MessageEncoder> >&) + 40 (WebProcess.cpp:616)
6   WebKit                        	0x000000018bdd94c0 IPC::Connection::dispatchSyncMessage(IPC::MessageDecoder&) + 196 (Connection.cpp:856)
7   WebKit                        	0x000000018bdd6ee8 IPC::Connection::dispatchMessage(std::__1::unique_ptr<IPC::MessageDecoder, std::__1::default_delete<IPC::MessageDecoder> >) + 136 (Connection.cpp:928)
8   WebKit                        	0x000000018bdd6d88 IPC::Connection::SyncMessageState::dispatchMessages(IPC::Connection*) + 240 (Connection.cpp:176)
9   JavaScriptCore                	0x0000000187091fcc WTF::RunLoop::performWork() + 172 (NoncopyableFunction.h:49)
10  JavaScriptCore                	0x00000001870921f8 WTF::RunLoop::performWork(void*) + 36 (RunLoopCF.cpp:38)
11  CoreFoundation                	0x0000000182875cbc __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 24 (CFRunLoop.c:1943)
12  CoreFoundation                	0x0000000182875604 __CFRunLoopDoSources0 + 524 (CFRunLoop.c:1989)
13  CoreFoundation                	0x0000000182873204 __CFRunLoopRun + 804 (CFRunLoop.c:2821)
14  CoreFoundation                	0x00000001827a45a4 CFRunLoopRunSpecific + 292 (CFRunLoop.c:3103)
15  Foundation                    	0x0000000183235bf8 -[NSRunLoop(NSRunLoop) runMode:beforeDate:] + 304 (NSRunLoop.m:367)
16  Foundation                    	0x000000018328a244 -[NSRunLoop(NSRunLoop) run] + 88 (NSRunLoop.m:389)
17  libxpc.dylib                  	0x000000018255af08 _xpc_objc_main + 660 (main.m:186)
18  libxpc.dylib                  	0x000000018255cc00 xpc_main + 200 (init.c:1438)
19  com.apple.WebKit.WebContent   	0x00000001000975e4 main + 376 (XPCServiceMain.mm:114)
20  libdyld.dylib                 	0x0000000182344600 start + 4

[Chris Dumez]

rdar://problem/26766720

[Chris Dumez]

Created attachment 282510 [details]
Patch

[Benjamin Poulain]

Comment on attachment 282510 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=282510&action=review

I am not sure to understand why this happens. I don't even know how you would test computeAutocorrectionContext() with the current infrastructure :(

> Source/WebKit2/WebProcess/WebPage/ios/WebPageIOS.mm:2194
> +    if (auto compositionRange = frame.editor().compositionRange()) {

For the love of FSM, use types, not auto.

[Chris Dumez]

Comment on attachment 282510 [details]
Patch

Clearing flags on attachment: 282510

Committed r202757: <http://trac.webkit.org/changeset/202757>

[Chris Dumez]

All reviewed patches have been landed.  Closing bug.