[Webkit-unassigned] [Bug 64256] REGRESSION(r90552): platform/mac/accessibility/html-slider-indicator.html fails

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=64256


Kent Tamura <tkent at chromium.org> changed:

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--- Comment #2 from Kent Tamura <tkent at chromium.org>  2011-07-11 02:33:28 PST ---
(From update of attachment 100256)
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(), ...

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