[webkit-reviews] review requested: [Bug 19907] REGRESSION(r34824-r34941): Reproducible crash trying to log in to MediaTemple.net Account Center : [Attachment 22141] Proposed patch

[bugzilla-daemon at webkit.org]

Cameron Zwarich (cpst) <cwzwarich at uwaterloo.ca> has asked  for review:
Bug 19907: REGRESSION(r34824-r34941): Reproducible crash trying to log in to
MediaTemple.net Account Center
https://bugs.webkit.org/show_bug.cgi?id=19907

Attachment 22141: Proposed patch
https://bugs.webkit.org/attachment.cgi?id=22141&action=edit

------- Additional Comments from Cameron Zwarich (cpst)
<cwzwarich at uwaterloo.ca>
Here's a patch that fixes the problem. We made NPN_SetException a no-op in
order to fix bug 19853, but an exception could also be set from JavaScript code
itself. Clearing exceptions after calling out to JavaScript code seems to be
the only fix besides properly implementing exceptions in the Netscape plugin
API. If we checked for an exception in Machine::execute() and returned jsNull()
if one was set, then we would probably be breaking a lot of legitimate calls to
JavaScript. The only case this will change is where JavaScript calls out to the
Netscape plugin API, and the Netscape plugin executes a single reentrant call
to JavaScript and then returns (a second call would cause a crash, just like in
this bug). In that case, there may currently be an exception returned that is
now missed with this patch.