Re: [2.6 patch] crypto/aes.c: array overrun

[David McCullough <david_mccullough@au.securecomputing.com>]

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Jivin Valdis.Kletnieks@vt.edu lays it down ...
> On Sat, 11 Mar 2006 13:41:16 +1100, Herbert Xu said:
> 
> > OK this is not pretty but it is actually correct.  Notice how we only
> > overstep the mark for E_KEY but never for D_KEY.  Since D_KEY is only
> > initialised after this, it is OK for us to trash the start of D_KEY.
> 
> I think a big comment block describing this behavior is called for,
> as it carries an implicit requirement that D_KEY and E_KEY remain
> adjacent in memory.  Anybody allocating space between them is in for
> a rude awakening....

Sounds like a bug waiting to happen to me.
Why not do something like the attached patch.

Cheers,
Davidm

-- 
David McCullough, david_mccullough@au.securecomputing.com, Ph:+61 734352815
Secure Computing - SnapGear  http://www.uCdot.org http://www.cyberguard.com

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Index: linux-2.6.x/crypto/aes.c
===================================================================
RCS file: linux-2.6.x/crypto/aes.c,v
retrieving revision 1.1.1.6
diff -u -r1.1.1.6 aes.c
--- linux-2.6.x/crypto/aes.c	31 Aug 2005 00:33:03 -0000	1.1.1.6
+++ linux-2.6.x/crypto/aes.c	14 Mar 2006 22:53:06 -0000
@@ -78,12 +78,11 @@
 
 struct aes_ctx {
 	int key_length;
-	u32 E[60];
-	u32 D[60];
+	u32 _KEYS[120];
 };
 
-#define E_KEY ctx->E
-#define D_KEY ctx->D
+#define E_KEY (&ctx->_KEYS[0])
+#define D_KEY (&ctx->_KEYS[60])
 
 static u8 pow_tab[256] __initdata;
 static u8 log_tab[256] __initdata;