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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Use WeakPtrs to avoid using deallocated Widgets and ScrollableAreas"
href="https://bugs.webkit.org/show_bug.cgi?id=156420">156420</a>
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<th>Summary</th>
<td>Use WeakPtrs to avoid using deallocated Widgets and ScrollableAreas
</td>
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<th>Classification</th>
<td>Unclassified
</td>
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<th>Product</th>
<td>WebKit
</td>
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<th>Version</th>
<td>WebKit Nightly Build
</td>
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<th>Hardware</th>
<td>All
</td>
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<th>OS</th>
<td>All
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>Normal
</td>
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<th>Priority</th>
<td>P2
</td>
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<th>Component</th>
<td>Event Handling
</td>
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<th>Assignee</th>
<td>webkit-unassigned@lists.webkit.org
</td>
</tr>
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<th>Reporter</th>
<td>bfulgham@webkit.org
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<pre>Bugs 150871 and 156409 were caused by Events destroying elements that were currently in use to handle wheel events. Since the EventHandler logic held onto raw pointers to these elements (not expecting them to be destroyed during the same method call), we would dereference these invalid pointers causing crashes and other problems.
We can do a better job by using WeakPtrs (instead of bare pointers) that will become null when the underlying object is destroyed. This will convert various use-after-free problems into null-pointer dereferences, which are much safer, and easier to find. By using proper null checking, we can avoid crashes and ensure proper behavior in these cases.</pre>
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