No, there could only have not more than 201 opcodes in a script. So you may have 198 OP_2DUP at most, i.e. 198 * 520 * 2 = 206kB
For OP_CAT, just check if the returned item is within the 520 bytes limit. > On 3 Jan 2017, at 11:27, Jeremy via bitcoin-dev > <bitcoin-dev@lists.linuxfoundation.org> wrote: > > It is an unfortunate script, but can't actually do that much it seems. The > MAX_SCRIPT_ELEMENT_SIZE = 520 Bytes. Thus, it would seem the worst you could > do with this would be to (10000-520*2)*520*2 bytes ~=~ 10 MB. > > Much more concerning would be the op_dup/op_cat style bug, which under a > similar script would certainly cause out of memory errors :) > > > > -- > @JeremyRubin <https://twitter.com/JeremyRubin> > <https://twitter.com/JeremyRubin> > On Mon, Jan 2, 2017 at 4:39 PM, Steve Davis via bitcoin-dev > <bitcoin-dev@lists.linuxfoundation.org > <mailto:bitcoin-dev@lists.linuxfoundation.org>> wrote: > Hi all, > > Suppose someone were to use the following pk_script: > > [op_2dup, op_2dup, op_2dup, op_2dup, op_2dup, ...(to limit)..., op_2dup, > op_hash160, <addr_hash>, op_equalverify, op_checksig] > > This still seems to be valid AFAICS, and may be a potential attack vector? > > Thanks. > > > _______________________________________________ > bitcoin-dev mailing list > bitcoin-dev@lists.linuxfoundation.org > <mailto:bitcoin-dev@lists.linuxfoundation.org> > https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev > <https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev> > > > _______________________________________________ > bitcoin-dev mailing list > bitcoin-dev@lists.linuxfoundation.org > https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
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