chakra-core/ChakraCore

ASSERTION fails in Array.prototype.copyWithin

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#6,458 opened on Jun 8, 2020

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Description

Hello, I run following code in ch 1.11.19(debug)，and it will crash by an assertion.

let b = [1.1, 2.2, 3.3];
b[4294967294] = 3;
Array.prototype.copyWithin.call(b, 0, 1);

Crash output:

ASSERTION 7690: (/.../ChakraCore-1.11.19/lib/Runtime/Library/JavascriptArray.cpp, line 9309) direction == -1 || (fromVal + count < MaxArrayLength && toVal + count < MaxArrayLength)
 Failure: (direction == -1 || (fromVal + count < MaxArrayLength && toVal + count < MaxArrayLength))
Illegal instruction

When reading the source code, I find that the if-condition and the asserts in else-branch are not mutually complemental. https://github.com/microsoft/ChakraCore/blob/c848d4d8d50c0dfb4a23540a9ee6cd023fa029c1/lib/Runtime/Library/JavascriptArray.cpp#L9286 The asserts in else-branch should be : Assert((fromVal + count) <= MaxArrayLength && (toVal + count) <= MaxArrayLength )

ISec Lab 2020.6.8

Contributor guide

Research direction
Inspect the assertion in JavascriptArray.cpp at line 9309. Verify that the condition in the else branch should be `(fromVal + count) <= MaxArrayLength && (toVal + count) <= MaxArrayLength`. Confirm and propose a fix by updating the assertion.
Tech stack
cpp
Domain
backend
Issue type
Bug
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2
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Half day
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Clear
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C++
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30