On Sat, 2016-10-15 at 18:16 +0100, Ard Biesheuvel wrote: > The CCM code goes out of its way to perform the CTR encryption of the > MAC using the subordinate CTR driver. To this end, it tweaks the > input and output scatterlists so the aead_req 'odata' and/or > 'auth_tag' fields [which may live on the stack] are prepended to the > CTR payload. This involves calling sg_set_buf() on addresses which > are not direct mapped, which is not supported. > Since the calculation of the MAC keystream involves a single call > into the cipher, to which we have a handle already given that the > CBC-MAC calculation uses it as well, just calculate the MAC keystream > directly, and record it in the aead_req private context so we can > apply it to the MAC in cypto_ccm_auth_mac(). This greatly simplifies > the scatterlist manipulation, and no longer requires scatterlists to > refer to buffers that may live on the stack. No objection from me, Herbert? I'm getting a bit nervous though - I'd rather have any fix first so people get things working again - so maybe I'll apply your other patch and mine first, and then we can replace yours by this later. johannes
