Kernel panic when using ccm(aes) with the Atmel AES HW accelerator

[Tudor Ambarus]

Hi, Romain,

On 10/18/2017 04:32 PM, Romain Izard wrote:
> my fix also led to a
> systematic oops when running the ccm(aes) test case.

The NULL deference appears because of a memory corruption issue.

atmel-aes does not implement ccm(aes), so the algorithm will be in the
following form: ccm_base(atmel-ctr-aes,cbcmac(aes-generic)).

ccm auth uses the first byte of the IV as length and eventually will
memset memory to zero based on that length (see set_msg_len()). CTR
overwrites the iv with the last ciphertext block and the length will be
wrong.

I will propose a fix, but I'm taking my time to better understand why
CTR requires to overwrite the iv with the last ciphertext block.

Cheers,
ta