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SubjectRe: [PATCH/proposal] dm-crypt: add digest-based iv generation mode
On Wed, Feb 25, 2004 at 03:25:24AM +0100, Christophe Saout wrote:
> Am Di, den 24.02.2004 schrieb Matt Mackall um 20:11:
> > > + int tfm_size = sizeof(*cc->digest) + cc->digest->__crt_alg->cra_ctxsize;
> > > + char tfm[tfm_size];
> > > [...]
> > > + memcpy(tfm, cc->digest, tfm_size);
> >
> > As this stands, it's rather scary.
> >
> > - it will quietly break when cryptoapi gets fiddled with
> Yes, and it's already broken. When putting a lot of stress to the
> filesystem data corruption pops up.
> It turned out the hmac code uses an additional scratch pad which is used
> in crypto_hmac_final (the "opad") which was kmalloc'ed. So it isn't even
> inside the context (the one after struct tfm with length cra_ctxsize).
> Why that? That kmalloc could have been avoided and the opad could store
> after the tfm struct too (or on the stack of the crypto_hmac_final or is
> it too large?). Yes, I know, ... but it would really be nice not to put
> locks around the calls.

This is insine, there is no reason to have that outside of function scope at

Here's the fix.

Uses the stack now (peak stack usage will not go up)

James - I'll wrap this one up with my other in one patch. This is a "look
see, say 'OK'" patch.


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