On Thu, Jun 17, 2021 at 04:08:15PM +1000, Michael Ellerman wrote:
> Kees Cook <keesc...@chromium.org> writes:
> > Fix typo in memcpy() where size should be CTR_RFC3686_NONCE_SIZE.
> >
> > Fixes: 030f4e968741 ("crypto: nx - Fix reentrancy bugs")
> > Cc: sta...@vger.kernel.org
> > Signed-off-by: Kees Cook <keesc...@chromium.org>
>
> Thanks.
>
> > ---
> > drivers/crypto/nx/nx-aes-ctr.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/crypto/nx/nx-aes-ctr.c b/drivers/crypto/nx/nx-aes-ctr.c
> > index 13f518802343..6120e350ff71 100644
> > --- a/drivers/crypto/nx/nx-aes-ctr.c
> > +++ b/drivers/crypto/nx/nx-aes-ctr.c
> > @@ -118,7 +118,7 @@ static int ctr3686_aes_nx_crypt(struct skcipher_request
> > *req)
> > struct nx_crypto_ctx *nx_ctx = crypto_skcipher_ctx(tfm);
> > u8 iv[16];
> >
> > - memcpy(iv, nx_ctx->priv.ctr.nonce, CTR_RFC3686_IV_SIZE);
> > + memcpy(iv, nx_ctx->priv.ctr.nonce, CTR_RFC3686_NONCE_SIZE);
> > memcpy(iv + CTR_RFC3686_NONCE_SIZE, req->iv, CTR_RFC3686_IV_SIZE);
> > iv[12] = iv[13] = iv[14] = 0;
> > iv[15] = 1;
>
> Where IV_SIZE is 8 and NONCE_SIZE is 4.
>
> And iv is 16 bytes, so it's not a buffer overflow.
>
> But priv.ctr.nonce is 4 bytes, and at the end of the struct, so it reads
> 4 bytes past the end of the nx_crypto_ctx, which is not good.
>
> But then immediately overwrites whatever it read with req->iv.
>
> So seems pretty harmless in practice?
Right -- there's no damage done, but future memcpy() FORTIFY work alerts
on this, so I'm going through cleaning all of these up. :)
--
Kees Cook
