On 08/24/18 09:22 PM, Herbert Xu wrote: > > > BTW. gcmaes_crypt_by_sg also contains GFP_ATOMIC and -ENOMEM, behind a > > > pretty complex condition. Do you mean that this condition is part of the > > > contract that the crypto API provides? > > > > This is an implementation defect. I think for this case we should > > fall back to software GCM if the accelerated version fails. > > > > > Should "req->src->offset + req->src->length < PAGE_SIZE" use "<=" instead? > > > Because if the data ends up at page boundary, it will use the atomic > > > allocation that can fail. > > > > This condition does look strange. It's introduced by the commit > > e845520707f85c539ce04bb73c6070e9441480be. Dave, what exactly is > > it meant to do? The aesni routines still require linear AAD data, the condition checks that the AAD data is linear, and if not, kmallocs and copies it to a linear buffer. Yes, the condition looks like it could be <= PAGE_SIZE, similar to the one in gcmaes_encrypt. Yes, we should fall back to software gcm if kmalloc fails, although AAD data is usually small, and it is probably worth having a small stack buffer before attempting to kmalloc.
