Bug 45779 – Exceptions are getting ignored on 64-bit Windows in the Web Process

• Status: RESOLVED
• Resolution: FIXED
• Component: WebKit2

[Jessie Berlin]

We should clear the PROCESS_CALLBACK_FILTER_ENABLED flag. Right now, it is not cleared, so exceptions thrown in callback routines are ignored, allowing the Web Process to enter into an inconsistent state and possibly resulting in a different exception.

In order to make this effective, hotfix 976038 (http://support.microsoft.com/kb/976038) will need to be installed on the 64 bit machines in question, so we should add that information to the tools.html page as well.

[Jessie Berlin]

Created attachment 67602 [details]
Clear the PROCESS_CALLBACK_FILTER_ENABLED flag

[Adam Roben (:aroben)]

Comment on attachment 67602 [details]
Clear the PROCESS_CALLBACK_FILTER_ENABLED flag

View in context: https://bugs.webkit.org/attachment.cgi?id=67602&action=prettypatch

> WebKit2/WebProcess/WebKitMain.cpp:82
> +static void disableProcessCallbackFilterForExceptions()
I think disableUserModeCallbackExceptionFilter would be a clearer name.

> WebKit2/WebProcess/WebKitMain.cpp:84
> +    DWORD dwFlags;
You should move this declaration to just before it's used.

> WebKit2/WebProcess/WebKitMain.cpp:104
> +    setPolicyPtr(dwFlags & ~0x1);
I think you should make a named constant for 0x1.

It would probably be useful to link to <http://blog.paulbetts.org/index.php/2010/07/20/the-case-of-the-disappearing-onload-exception-user-mode-callback-exceptions-in-x64/>, at least in your ChangeLog.

> WebKitSite/building/tools.html:63
> +<li><p>Optional: Hotfix for 64-bit Windows to disable the process callback filter for exceptions</p>
I'd say "user-mode" instead of "process" here.

r=me

[Jessie Berlin]

(In reply to comment #2)
> (From update of attachment 67602 [details])
> View in context: https://bugs.webkit.org/attachment.cgi?id=67602&action=prettypatch
> 
> > WebKit2/WebProcess/WebKitMain.cpp:82
> > +static void disableProcessCallbackFilterForExceptions()
> I think disableUserModeCallbackExceptionFilter would be a clearer name.

Changed.

> 
> > WebKit2/WebProcess/WebKitMain.cpp:84
> > +    DWORD dwFlags;
> You should move this declaration to just before it's used.

Moved to right above the if statement.

> 
> > WebKit2/WebProcess/WebKitMain.cpp:104
> > +    setPolicyPtr(dwFlags & ~0x1);
> I think you should make a named constant for 0x1.

Added a #define PROCESS_CALLBACK_FILTER_ENABLED 0x1 closer to the top of the file so that it matches the documentation.

> 
> It would probably be useful to link to <http://blog.paulbetts.org/index.php/2010/07/20/the-case-of-the-disappearing-onload-exception-user-mode-callback-exceptions-in-x64/>, at least in your ChangeLog.
> 

Put it both in the ChangeLog and in the comment in the function.

> > WebKitSite/building/tools.html:63
> > +<li><p>Optional: Hotfix for 64-bit Windows to disable the process callback filter for exceptions</p>
> I'd say "user-mode" instead of "process" here.

Changed.

> 
> r=me

Thanks!

[Jessie Berlin]

Comment on attachment 67602 [details]
Clear the PROCESS_CALLBACK_FILTER_ENABLED flag

Committed in r67501
http://trac.webkit.org/changeset/67501