RFR: 8233747: JVM crash in com.sun.webkit.dom.DocumentImpl.createAttribute

[Arun Joseph]

On Thu, 28 Nov 2019 13:16:19 GMT, Arun Joseph <ajoseph at openjdk.org> wrote:

> On Wed, 20 Nov 2019 15:04:07 GMT, Kevin Rushforth <kcr at openjdk.org> wrote:
> 
>> On Wed, 20 Nov 2019 07:05:40 GMT, Arun Joseph <ajoseph at openjdk.org> wrote:
>> 
>>> Issue: Native part of WebView throws a DOMException and then, continues executing the rest of the function assuming that value is present. This causes the JVM to crash when retrieving the value.
>>> 
>>> Fix: Return from the function if exception was raised (code is similar to exception handling in [WebKitLegacy/java/DOM/JavaTreeWalker.cpp](https://github.com/openjdk/jfx/blob/master/modules/javafx.web/src/main/native/Source/WebKitLegacy/java/DOM/JavaTreeWalker.cpp))
>>> 
>>> This fix also needs to be applied to all function calls in [WebKitLegacy/java/DOM](https://github.com/openjdk/jfx/tree/master/modules/javafx.web/src/main/native/Source/WebKitLegacy/java/DOM) functions which raises DOMError similar to createAttributeImpl().
>>> 
>>> ----------------
>>> 
>>> Commits:
>>>  - acc52780: 8233747: JVM crash in com.sun.webkit.dom.DocumentImpl.createAttribute
>>> 
>>> Changes: https://git.openjdk.java.net/jfx/pull/47/files
>>>  Webrev: https://webrevs.openjdk.java.net/jfx/47/webrev.00
>>>   Issue: https://bugs.openjdk.java.net/browse/JDK-8233747
>>>   Stats: 7 lines in 1 file changed: 6 ins; 0 del; 1 mod
>>>   Patch: https://git.openjdk.java.net/jfx/pull/47.diff
>>>   Fetch: git fetch https://git.openjdk.java.net/jfx pull/47/head:pull/47
>> 
>> The proposed fix seems more like a workaround to me. There are dozens of very similar calls to `raiseOnDOMError` in this and other files, so I would think a more general solution is needed.
> 
> For calls to `raiseOnDOMError()` with argument of type `ExceptionOr<Ref<T>>`, the returned value is again passed through `WTF::getPtr()`. This doesn't modify the value returned, but removing it will require changing about 40 function calls.

In `createAttributeImpl` function in [JavaDocument.cpp](https://github.com/openjdk/jfx/blob/master/modules/javafx.web/src/main/native/Source/WebKitLegacy/java/DOM/JavaDocument.cpp), the value returned from `raiseOnDOMError` is passed to `WTF::getPtr` function. Now there are two calls to `WTF::getPtr`, one from `raiseOnDOMError` in the return statement and another in `createAttributeImpl`, instead of just one. So, this approach has an unnecessary call to `WTF::getPtr` which, if needed, has to removed at the `createAttributeImpl` end. This doesn't modify the `Attr` object returned because `WTF::getPtr` returns the same pointer when called multiple times.

PR: https://git.openjdk.java.net/jfx/pull/47