pallet-collective: Unbounded ProposalOf causes weight under-estimation in close extrinsic #10209
Description
Description
The close extrinsic takes length_bound as a parameter for calculating a worst-case scenario weight for the call, but this can result in an under-estimation when the length_bound provided is lower than the real encoded call stored in ProposalOf.
When the length_bound is less than the real length of the proposal, the call will fail as expected with WrongProposalLength, but the charged weight will be less than it should, since it reads the entire encoded value from storage to be able to assert that length_bound is greater or equal to the real length of the proposal call.
Weight calculation:
polkadot-sdk/substrate/frame/collective/src/lib.rs
Lines 807 to 830 in b365061
Length check:
polkadot-sdk/substrate/frame/collective/src/lib.rs
Lines 1138 to 1142 in b365061
As a solution for this, the pallet collective should leverage the preimage pallet which offers mechanisms to correctly handle bounds. More context on what can be done: paritytech/substrate#11649
Impact
The impact seems minimal because only members of the collective can create proposals.