linux-kernel - [PATCH 7/8 v2] crypto: replace memset by memzero

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Message-Id: <1417367029-32762-8-git-send-email-Julia.Lawall@lip6.fr>
Date:	Sun, 30 Nov 2014 18:03:48 +0100
From:	Julia Lawall <Julia.Lawall@...6.fr>
To:	Herbert Xu <herbert@...dor.apana.org.au>
Cc:	kernel-janitors@...r.kernel.org,
	"David S. Miller" <davem@...emloft.net>,
	Russell King <linux@....linux.org.uk>,
	linux-crypto@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 7/8 v2] crypto: replace memset by memzero_explicit

From: Julia Lawall <Julia.Lawall@...6.fr>

Memset on a local variable may be removed when it is called just before the
variable goes out of scope.  Using memzero_explicit defeats this
optimization.  A simplified version of the semantic patch that makes this
change is as follows: (http://coccinelle.lip6.fr/)

// <smpl>
@@
identifier x;
type T;
@@

{
... when any
T x[...];
... when any
    when exists
- memset
+ memzero_explicit
  (x,
-0,
  ...)
... when != x
    when strict
}
// </smpl>

This change was suggested by Daniel Borkmann <dborkman@...hat.com>

Signed-off-by: Julia Lawall <Julia.Lawall@...6.fr>

---
Daniel Borkmann suggested that these patches could go through Herbert Xu's
cryptodev tree.

I was not able to compile this one.

v2: fixed email address

 arch/arm/crypto/sha512_neon_glue.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm/crypto/sha512_neon_glue.c b/arch/arm/crypto/sha512_neon_glue.c
index f3452c6..b124dce 100644
--- a/arch/arm/crypto/sha512_neon_glue.c
+++ b/arch/arm/crypto/sha512_neon_glue.c
@@ -241,7 +241,7 @@ static int sha384_neon_final(struct shash_desc *desc, u8 *hash)
 	sha512_neon_final(desc, D);
 
 	memcpy(hash, D, SHA384_DIGEST_SIZE);
-	memset(D, 0, SHA512_DIGEST_SIZE);
+	memzero_explicit(D, SHA512_DIGEST_SIZE);
 
 	return 0;
 }

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