Le 20/01/2021 à 23:23, Ard Biesheuvel a écrit :

On Wed, 20 Jan 2021 at 19:59, Christophe Leroy
[off-list ref] wrote:

quoted

Talitos Security Engine AESU considers any input
data size that is not a multiple of 16 bytes to be an error.
This is not a problem in general, except for Counter mode
that is a stream cipher and can have an input of any size.

Test Manager for ctr(aes) fails on 4th test vector which has
a length of 499 while all previous vectors which have a 16 bytes
multiple length succeed.

As suggested by Freescale, round up the input data length to the
nearest 16 bytes.

Fixes: 5e75ae1b3cef ("crypto: talitos - add new crypto modes")
Signed-off-by: Christophe Leroy <redacted>

Doesn't this cause the hardware to write outside the given buffer?

Only the input length is modified. Not the output length.

The ERRATA says:

The input data length (in the descriptor) can be rounded up to the nearest 16B. Set the
data-in length (in the descriptor) to include X bytes of data beyond the payload. Set the
data-out length to only output the relevant payload (don't need to output the padding).
SEC reads from memory are not destructive, so the extra bytes included in the AES-CTR
operation can be whatever bytes are contiguously trailing the payload.