GMS-2022-2938: DOS and excessive memory usage when passing untrusted user input to to dag import

go-ipfs nodes crash when trying to import certain malformed CAR files due to an issue in the go-car dependency. This impacts nodes running ipfs dag import on untrusted user inputs, for example, pinning services with a car ingest endpoint. This include the corresponding HTTP RPC API v0/dag/import endpoint. An attacker controlling the car file passed in can also make the node allocate arbitrary sized buffers creating memory exhaustion attacks.