[webkit-reviews] review denied: [Bug 64256] REGRESSION(r90552): platform/mac/accessibility/html-slider-indicator.html fails : [Attachment 100256] Patch

[bugzilla-daemon at webkit.org]

Kent Tamura <tkent at chromium.org> has denied Shinya Kawanaka
<shinyak at google.com>'s request for review:
Bug 64256: REGRESSION(r90552):
platform/mac/accessibility/html-slider-indicator.html fails
https://bugs.webkit.org/show_bug.cgi?id=64256

Attachment 100256: Patch
https://bugs.webkit.org/attachment.cgi?id=100256&action=review

------- Additional Comments from Kent Tamura <tkent at chromium.org>
View in context: https://bugs.webkit.org/attachment.cgi?id=100256&action=review


> Source/WebCore/html/RangeInputType.cpp:224
>	   element()->dispatchFormControlChangeEvent();
> +
> +	   if (AXObjectCache::accessibilityEnabled())
> +	      
element()->document()->axObjectCache()->postNotification(element()->renderer(),
AXObjectCache::AXValueChanged, true);
>      }

dispatchFormControlChangeEvent() dispatch an 'change' event, so a JavaScript
code runs in it.
The JavaScriptCode can delete the parent <input>, and can change the type of
the <input>.  So accessing element() after dispatchFormControlChangeEvent()
causes a use-after-free.

You need to protect a reference of element() by RefPtr<> in order to keep
<input> alive and in order to avoid 'this' access.
RefPtr<HTMLInputELement> input = element();
input->dispatchFormControlChangeEvent();
if (...)
    input->document()->axObjectCache()->postNotification(input->renderer(), ...