Re: [PATCH] crypto: xts_crypt() return if walk.nbytes is 0

From: Herbert Xu
Date: Fri Aug 20 2021 - 08:53:41 EST

On Fri, Aug 20, 2021 at 01:14:52PM +0200, Ard Biesheuvel wrote:
> In spite of that, I have a slight preference for this version, given
> that it makes it obvious that we bail on two separate conditions:
> - an error has occurred
> - no error has occurred but the resulting walk is empty
> Testing walk.nbytes only needlessly obfuscates the code, as we need to
> return 'err' in the end anyway.

I disagree, this is how most skcipher walkers are structured, they
never explicitly test on err and only terminate the loop when
walk->nbytes hits zero, in which case err is returned as is.

I don't see why this particular skcipher walker should deviate
from that paradigm. In fact it is exactly that deviation that
caused the bug in the first instance.

Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
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