Bug 77076 – NULL ptr in WebCore::firstPositionInNode

• Status: RESOLVED
• Resolution: FIXED
• Component: HTML Editing

[Berend-Jan Wever]

Created attachment 124073 [details]
Repro

Detailed report: https://cluster-fuzz.appspot.com/testcase?key=15610811

Uploader: [e-mail]

Crash Type: UNKNOWN
Crash Address: 0x000000000024
Crash State:
  - crash stack -
  WebCore::firstPositionInNode
  WebCore::CompositeEditCommand::moveParagraphs
  WebCore::CompositeEditCommand::moveParagraphContentsToNewBlockIfNecessary
  
Regressed: https://cluster-fuzz.appspot.com/revisions?range=108839:108881

Minimized Testcase (1.24 Kb): https://cluster-fuzz.appspot.com/download/AMIfv976OjoT6ps69jrMB2vbO99x3mZt1e4CryNTt9GticHO3OHDsVs-W0NFwNbZO-Ck4hfn_oC4ASIq4YedCfZTO63e_mhyUcELKDhWfiAZTqgHdzT90Q1oebl0hv-pQSNcfZtKdM7VppVcW0GUAJbngOUoCvXQ_w

Repro:
<script>
  function main(){
    document.designMode="on";
    document.execCommand("SelectAll");  }
    document.execCommand("JustifyLeft", false);  }
    try{window._NodeList_E7D=document.open("name_18446744073709551613")}catch(e){console.log(e)};  }
  }
  document.addEventListener("DOMCharacterDataModified",main,true);
  setInterval(main, 100);
</script>

*j2LCS'

[Berend-Jan Wever]

A similar repro triggers a crash in lastPositionInNode, so I believe it to be a variation:

<script>
  function main(){
    document.designMode="on";/*exec*/
    document.execCommand("ForwardDelete");/*exec*/
    document.execCommand("Indent", false);/*js_om*/
  }
</script>

<script type="text/javascript">
  document.addEventListener("DOMCharacterDataModified",main,true);
  setInterval(main, 100);
</script>
<plaintext class="class1"</plaintext>
<input class="class3" id="id_684" type="button"

Could not reproduce on
 Win7 27.0.1453.110 (Official Build 202711) m

Some patches so far fixed this.