Messages in this thread | | | Subject | Re: [PATCH 1/2] crypto: talitos - Work around SEC6 ERRATA (AES-CTR mode data size error) | From | Christophe Leroy <> | Date | Thu, 21 Jan 2021 06:35:06 +0100 |
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Le 20/01/2021 à 23:23, Ard Biesheuvel a écrit : > On Wed, 20 Jan 2021 at 19:59, Christophe Leroy > <christophe.leroy@csgroup.eu> wrote: >> >> 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 <christophe.leroy@csgroup.eu> > > 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.
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