Messages in this thread | | | Date | Wed, 22 Aug 2012 19:38:59 +0300 | Subject | Re: [RFC v2 1/7] integrity: added digest calculation function | From | "Kasatkin, Dmitry" <> |
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On Mon, Aug 20, 2012 at 5:59 AM, Rusty Russell <rusty@rustcorp.com.au> wrote: > On Wed, 15 Aug 2012 21:43:06 +0300, Dmitry Kasatkin <dmitry.kasatkin@intel.com> wrote: >> + } else { >> + struct { >> + struct shash_desc shash; >> + char ctx[crypto_shash_descsize(tfm)]; >> + } desc; > > Linus had a rant a while ago about using variable-sized stack vars in > the kernel (can't find a reference right now, sorry). > > The problem is that either you know there's a limit to > crypto_shash_descsize(), in which case you can just use this here, or > you don't know, in which case, this risks a stack oveflow. > > Cheers, > Rusty.
Well... descriptor size is a algo specific but constant... just sizeof(some struct). So there is no possibility to force overflow unless someone implement some algo driver which uses too big descriptor size.
- Dmitry
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