Messages in this thread | | | From | Arnd Bergmann <> | Date | Tue, 17 Jul 2018 22:59:00 +0200 | Subject | Re: [PATCH v4 11/14] treewide: Prepare to remove VLA usage for AHASH_REQUEST_ON_STACK |
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On Sun, Jul 15, 2018 at 6:28 AM, Kees Cook <keescook@chromium.org> wrote: > > After my ahash to shash conversions, only ccm is left as an ahash > user, since it actually uses sg. But with the hard-coded value reduced > to 376, this doesn't trip the frame warnings any more. :) > > I'll send an updated series soon.
Maybe we should get rid of that one as well then and remove AHASH_REQUEST_ON_STACK()?
I see that Ard (now on Cc) added this usage only recently. Looking at the code some more, I also find that the descsize is probably much smaller than 376 for all possible cases of "cbcmac(*)", either alg->cra_blocksize plus a few bytes or sizeof(mac_desc_ctx) (i.e. 20) for arch/arm64/crypto/aes-glue.c.
Walking the sglist here means open-coding a shash_ahash_update() implementation in crypto_ccm_auth(), that that doesn't seem to add much complexity over what it already has to do to chain the sglist today.
Arnd
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