Re: [BUG] SLOB breaks Crypto

From: Matt Mackall
Date: Tue May 18 2010 - 15:06:37 EST


On Tue, 2010-05-18 at 20:27 +1000, Herbert Xu wrote:
> On Tue, May 18, 2010 at 10:17:35AM +0200, Adrian-Ken Rueegsegger wrote:
> >
> > As noted in my other mail [1] it seems like the HMAC tests trigger these
> > errors.
>
> Thanks for all the detective work!
>
> I think the problem is this changeset:
>
> commit 6eb7228421c01ba48a6a88a7a5b3e71cfb70d4a9
> Author: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
> Date: Tue Jan 8 17:16:44 2008 +1100
>
> [CRYPTO] api: Set default CRYPTO_MINALIGN to unsigned long long
>
> Thanks to David Miller for pointing out that the SLAB (or SLOB/SLUB)
> cache uses the alignment of unsigned long long if the architecture
> kmalloc/slab alignment macros are not defined.
>
> This patch changes the CRYPTO_MINALIGN so that it uses the same default
> value.
>
> Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
>
> diff --git a/include/linux/crypto.h b/include/linux/crypto.h
> index 0aba104..5e02d1b 100644
> --- a/include/linux/crypto.h
> +++ b/include/linux/crypto.h
> @@ -90,13 +90,11 @@
> #define CRYPTO_MINALIGN ARCH_KMALLOC_MINALIGN
> #elif defined(ARCH_SLAB_MINALIGN)
> #define CRYPTO_MINALIGN ARCH_SLAB_MINALIGN
> +#else
> +#define CRYPTO_MINALIGN __alignof__(unsigned long long)
> #endif
>
> -#ifdef CRYPTO_MINALIGN
> #define CRYPTO_MINALIGN_ATTR __attribute__ ((__aligned__(CRYPTO_MINALIGN)))
> -#else
> -#define CRYPTO_MINALIGN_ATTR
> -#endif
>
> struct scatterlist;
> struct crypto_ablkcipher;
>
> So evidently the assumption made in this change does not work on
> SLOB since it only guarantees __alignof__(unsigned long).

Bingo. Feel free to stick this on your revert:

Acked-by: Matt Mackall <mpm@xxxxxxxxxxx>

Looks like we should ensure that ARCH_KMALLOC_MINALIGN is always
defined.

--
Mathematics is the supreme nostalgia of our time.


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