EIP1271 is not implement correctly in GnosisSafe

[nivida]

Description

The magic value checked here is not the correct (the old one) and so if someone is creating a GnosisSafe with mainly contract wallets is it the case that funds previously sent to the GnosisSafe are locked. Could be that this bug is eligible for the bug bounty program.

Environment

• Compiler version:
• Compiler options (if applicable, e.g. optimizer enabled):
• Framework/IDE (e.g. Truffle or Remix):
• EVM execution environment / backend / blockchain client:
• Operating system:

Steps to reproduce

Create a GnosisSafe with eg only Argent contract wallets or with enough so that the threshold isn't reachable and try to approve a transaction.

[rmeissner]

it is the old magic value, because it also calls the old function isValidSignature(bytes,bytes).

It is planned to remove this logic completely. See https://forum.gnosis-safe.io/t/safe-contract-v2/87