The theoretical attack there is that one could selectively garble the (decrypted) parts of your storage, and thus destroy the contents of e.g. your configuratio

The theoretical attack there is that one could selectively garble the (decrypted) parts of your storage, and thus destroy the contents of e.g. your configuration files. E.g. they could corrupt your firewall configuration file and thus leave your computer open to outside network connections. I don't think this has been done in practice, and it's probably not very feasible. Such an attack could not be detected, because the encryption modes commonly used do not provide integrity protection. This is due to the desire to have equal sizes for both the encrypted and plaintext sectors (as far as I understand, that's an efficiency/ease of implementation concern). Incidentally, you can easily see that such a scheme can never provide integrity, since the encryption operation has to be a permutation, and you have to be able to decrypt any ciphertext.