diff mbox

[6/8,v2] crypto: replace memset by memzero_explicit

Message ID 1417367029-32762-7-git-send-email-Julia.Lawall@lip6.fr (mailing list archive)
State Accepted
Delegated to: Herbert Xu
Headers show

Commit Message

Julia Lawall Nov. 30, 2014, 5:03 p.m. UTC 
From: Julia Lawall <Julia.Lawall@lip6.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@redhat.com>

Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>

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

v2: fixed email address

 arch/powerpc/crypto/sha1.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)


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Comments

Michael Ellerman Dec. 1, 2014, 12:58 a.m. UTC | #1 
On Sun, 2014-11-30 at 18:03 +0100, Julia Lawall wrote:
> From: Julia Lawall <Julia.Lawall@lip6.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
> 
> Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
> 
> ---
> Daniel Borkmann suggested that these patches could go through Herbert Xu's
> cryptodev tree.

That's fine by me:

Acked-by: Michael Ellerman <mpe@ellerman.id.au>

cheers


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diff mbox

Patch

diff --git a/arch/powerpc/crypto/sha1.c b/arch/powerpc/crypto/sha1.c
index 0f88c7b..d3feba5 100644
--- a/arch/powerpc/crypto/sha1.c
+++ b/arch/powerpc/crypto/sha1.c
@@ -66,7 +66,7 @@  static int sha1_update(struct shash_desc *desc, const u8 *data,
 			src = data + done;
 		} while (done + 63 < len);
 
-		memset(temp, 0, sizeof(temp));
+		memzero_explicit(temp, sizeof(temp));
 		partial = 0;
 	}
 	memcpy(sctx->buffer + partial, src, len - done);