Can make a big sized tx that is able to be committed

[Thunnini]

Summary of Bug

It is possible to make a big sized transaction because length of int is not restricted when amino decoding, and there is no restriction on denom's length in coin.
https://github.com/cosmos/cosmos-sdk/blob/develop/types/int.go#L59

Steps to Reproduce

By making cli skip to validate a coin like this, I can make transaction's size big. Of course, that transaction couldn't succeed. However, that can be passed ante handler, so honest validators will commit this transaction.
EX) gaiacli tx send --from test --to cosmos134zr33w96gsjwmxdwz6lmucpldnsszca23t88e --amount 9999999999999999999999testtttttttttt --chain-id gaia-10k --fees 1stake
I think it is possible to attack a DOS because attackers can make a big transaction with just consuming fees.

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For Admin Use

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[alexanderbez]

How exactly would this be a DOS attack vector besides committing these large txs to disk?

[Thunnini]

I think a big transaction prevents other's transaction from committing because there is a limit on max block size. In addition, I suspect that block which has useless big transactions can increase the cost of network per nodes. Currently, cosmos-sdk is not charging fees or gas depending on the transaction's size, attackers can create transactions that lay more burden on nodes than they are consuming.

[jackzampolin]

Related, that we are working on for this release: #3256

[github-actions]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[tac0turtle]

reopen if applicable