chakra-core/ChakraCore

ASSERTION fails in Array.prototype.copyWithin

Open

#6,458 opened on Jun 8, 2020

View on GitHub
 (8 comments) (1 reaction) (0 assignees)JavaScript (1,374 forks)batch import
Buggood first issue

Repository metrics

Stars
 (9,000 stars)
PR merge metrics
 (No merged PRs in 30d)

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
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
Half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
C++
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
30