Microsoft Edge Chakra JIT - Escape Analysis Bug

Microsoft Edge Chakra JIT - Escape Analysis Bug / Escape analysis: https://en.wikipedia.org/wiki/Escapeanalysis Chakra fails to detect if "tmp" escapes the scope, allocates it to the stack. This may lead to dereference uninitialized stack values. PoC: / function opt let tmp = ; tmp0 = tmp; return...

Microsoft Edge Chakra JIT - BackwardPass::RemoveEmptyLoopAfterMemOp Does not Insert Branches

Exploit for windows platform in category dos / poc / The optimizations for memory operations may leave empty loops as follows: for let i = 0; i arr.length; i++ arri = 0; Becomes: Memsetarr, 0, arr.length; for let i = 0; i arr.length; i++ // empty! These empty loops will be removed by...

Microsoft Edge Chakra JIT - BackwardPass::RemoveEmptyLoopAfterMemOp Does not Insert Branches

/ The optimizations for memory operations may leave empty loops as follows: for let i = 0; i arr.length; i++ arri = 0; Becomes: Memsetarr, 0, arr.length; for let i = 0; i arr.length; i++ // empty! These empty loops will be removed by "BackwardPass::RemoveEmptyLoopAfterMemOp". But this method just...

Microsoft Edge Chakra JIT - Op_MaxInAnArray and Op_MinInAnArray can Explicitly call User-Defined JavaScript Functions

Microsoft Edge Chakra JIT - OpMaxInAnArray and OpMinInAnArray can Explicitly call User-Defined JavaScript Functions / 1. Call patterns like "Math.max.applyMath, 1, 2, 3, 4, 5" and "Math.max.applyMath, arr" can be optimized to directly call the method "JavascriptMath::MaxInAnArray" in the Inline...

Microsoft Edge Chakra JIT - Escape Analysis Bug

/ Escape analysis: https://en.wikipedia.org/wiki/Escapeanalysis Chakra fails to detect if "tmp" escapes the scope, allocates it to the stack. This may lead to dereference uninitialized stack values. PoC: / function opt let tmp = ; tmp0 = tmp; return tmp0; function main for let i = 0; i 0x1000; i+...

Microsoft Edge Chakra JIT - Op_MaxInAnArray and Op_MinInAnArray can Explicitly call User-Defined JavaScript Functions

/ 1. Call patterns like "Math.max.applyMath, 1, 2, 3, 4, 5" and "Math.max.applyMath, arr" can be optimized to directly call the method "JavascriptMath::MaxInAnArray" in the Inline Phase. 2. The method takes the original method "Math.max" as the first parameter and the arguments object as the seco...

Microsoft Edge Chakra JIT - Op_MaxInAnArray and Op_MinInAnArray can Explicitly call User-Defined Jav

Exploit for windows platform in category dos / poc / 1. Call patterns like "Math.max.applyMath, 1, 2, 3, 4, 5" and "Math.max.applyMath, arr" can be optimized to directly call the method "JavascriptMath::MaxInAnArray" in the Inline Phase. 2. The method takes the original method "Math.max" as the...

Microsoft Edge Chakra JIT - Escape Analysis Bug Exploit

Exploit for windows platform in category dos / poc / Escape analysis: https://en.wikipedia.org/wiki/Escapeanalysis Chakra fails to detect if "tmp" escapes the scope, allocates it to the stack. This may lead to dereference uninitialized stack values. PoC: / function opt let tmp = ; tmp0 = tmp;...

Experts Weigh In On Spectre Patch Challenges

The race to patch against the Meltdown and Spectre processor vulnerabilities disclosed last week is on. As of today, there are no known exploits in the wild impacting vulnerable Intel, AMD and ARM devices. Currently, vendors are focused on three main mitigation efforts. Patches that address the...

CVE-2017-17862

kernel/bpf/verifier.c in the Linux kernel through 4.14.8 ignores unreachable code, even though it would still be processed by JIT compilers. This behavior, also considered an improper branch-pruning logic issue, could possibly be used by local users for denial of service...

CVE-2017-17862

kernel/bpf/verifier.c in the Linux kernel through 4.14.8 ignores unreachable code, even though it would still be processed by JIT compilers. This behavior, also considered an improper branch-pruning logic issue, could possibly be used by local users for denial of service...

Microsoft Edge Chakra CFG Bypass Due To Bug In ServerFreeAllocation Vulnerability

Charka suffers from a CFG bypass due to a bug in ServerFreeAllocation. Chakra: CFG bypass due to a bug in ServerFreeAllocation CVE-2017-11874 Chakra JIT server exposes a ServerFreeAllocation method that can be used to free an existing JIT allocation for example when the corresponding function get...

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 fx printx; function x printx; The following code in...

Microsoft Edge: Chakra: JIT: GlobOpt::OptTagChecks must consider IsLoopPrePass properly(CVE-2017-11840)

There's one more place that emits a BailOnNotObject opcode. Here's a snippet of GlobOpt::OptTagChecks. if valueType.CanBeTaggedValue && !valueType.HasBeenNumber && this-IsLoopPrePass || !this-currentBlock-loop ValueType newValueType = valueType.SetCanBeTaggedValuefalse; // Split out the tag check...

Microsoft Edge: Chakra: JIT: BailOutOnTaggedValue bailouts can be generated for constant values(CVE-2017-11839)

In the Chakra's JIT compilation process, it stores variables' type information by basic block. function optb let o; if b // BASIC BLOCK a o = ; else // BASIC BLOCK b o = 1.1; // BASIC BLOCK c return o; For example, let's think the above code gets optimized. At the basic block a, the type of "o"...

Microsoft Edge: Chakra: JIT: Inline::InlineCallApplyTarget_Shared doesn't return the return instruction(CVE-2017-11841)

Here's a snippet of Inline::Optimize. FOREACHINSTREDITINGinstr, instrNext, func-mheadInstr switch instr-mopcode case Js::OpCode::Label: ... if instr-AsLabelInstr-misForInExit Assertthis-currentForInDepth != 0; // The PoC hits this this-currentForInDepth--; break; case...

Microsoft Edge Chakra JIT - BailOutOnTaggedValue Bailouts Type Confusion

Microsoft Edge Chakra JIT - BailOutOnTaggedValue Bailouts Type Confusion / Source: https://bugs.chromium.org/p/project-zero/issues/detail?id=1364 1. In the Chakra's JIT compilation process, it stores variables' type information by basic block. function optb let o; if b // BASIC BLOCK a o = ; else...

Microsoft Edge Chakra JIT - 'GlobOpt::OptTagChecks' Must Consider IsLoopPrePass Properly

/ Source: https://bugs.chromium.org/p/project-zero/issues/detail?id=1365 Some background: https://bugs.chromium.org/p/project-zero/issues/detail?id=1364 There's one more place that emits a BailOnNotObject opcode. Here's a snippet of GlobOpt::OptTagChecks. if valueType.CanBeTaggedValue &&...

Microsoft Edge Chakra JIT - Inline::InlineCallApplyTarget_Shared does not Return the return Instruction

Microsoft Edge Chakra JIT - Inline::InlineCallApplyTargetShared does not Return the return Instruction / Source: https://bugs.chromium.org/p/project-zero/issues/detail?id=1366 Here's a snippet of Inline::Optimize. FOREACHINSTREDITINGinstr, instrNext, func-mheadInstr switch instr-mopcode case...

Microsoft Edge Chakra JIT - 'BailOutOnTaggedValue' Bailouts Type Confusion

/ Source: https://bugs.chromium.org/p/project-zero/issues/detail?id=1364 1. In the Chakra's JIT compilation process, it stores variables' type information by basic block. function optb let o; if b // BASIC BLOCK a o = ; else // BASIC BLOCK b o = 1.1; // BASIC BLOCK c return o; For example, let's...