linux-kernel - Re: [BUG] SLOB breaks Crypto

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Date:	Tue, 18 May 2010 20:27:01 +1000
From:	Herbert Xu <herbert@...dor.apana.org.au>
To:	Adrian-Ken Rueegsegger <ken@...elabs.ch>
Cc:	Matt Mackall <mpm@...enic.com>,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	michael-dev@...i-braun.de, Pekka Enberg <penberg@...helsinki.fi>,
	linux-kernel@...r.kernel.org, linux-crypto@...r.kernel.org,
	Atsushi Nemoto <anemo@....ocn.ne.jp>,
	"David S. Miller" <davem@...emloft.net>
Subject: Re: [BUG] SLOB breaks Crypto

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@...dor.apana.org.au>
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@...dor.apana.org.au>

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).

I think the simplest fix is to revert this changeset.

Cheers,
-- 
Visit Openswan at http://www.openswan.org/
Email: Herbert Xu ~{PmV>HI~} <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
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