Re: Deadlock when using crypto API for block devices
From: Mikulas Patocka
Date: Fri Aug 24 2018 - 09:00:07 EST
On Fri, 24 Aug 2018, Mikulas Patocka wrote:
> On Fri, 24 Aug 2018, Herbert Xu wrote:
> > On Fri, Aug 24, 2018 at 07:06:32AM -0400, Mikulas Patocka wrote:
> > >
> > > A quick search through the crypto code shows that ahash_save_req and
> > > seqiv_aead_encrypt return -ENOMEM.
> > >
> > > Will you fix them?
> > These only trigger for unaligned buffers. It would be much better
> > if dm-crypt can ensure that the input/output is properly unaligned
> > and if otherwise do the allocation in dm-crypt.
> But we are relying here on an implementation detail and not on contract.
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?
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.