Nov 30 2014

crypto: sparc – replace memset by memzero_explicit 

Author: 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/)

// 
@@
identifier x;
type T;
@@

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

This change was suggested by Daniel Borkmann 

Signed-off-by: Julia Lawall 
Signed-off-by: Herbert Xu 

---
 arch/sparc/crypto/sha256_glue.c | 2 +-
 arch/sparc/crypto/sha512_glue.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)
 
diff --git a/arch/sparc/crypto/sha256_glue.c b/arch/sparc/crypto/sha256_glue.c
index 41f27cc..285268c 100644
--- a/arch/sparc/crypto/sha256_glue.c
+++ b/arch/sparc/crypto/sha256_glue.c
@@ -135,7 +135,7 @@ static int sha224_sparc64_final(struct shash_desc *desc, u8 *hash)
 	sha256_sparc64_final(desc, D);
 
 	memcpy(hash, D, SHA224_DIGEST_SIZE);
-	memset(D, 0, SHA256_DIGEST_SIZE);
+	memzero_explicit(D, SHA256_DIGEST_SIZE);
 
 	return 0;
 }
diff --git a/arch/sparc/crypto/sha512_glue.c b/arch/sparc/crypto/sha512_glue.c
index 9fff885..11eb36c 100644
--- a/arch/sparc/crypto/sha512_glue.c
+++ b/arch/sparc/crypto/sha512_glue.c
@@ -139,7 +139,7 @@ static int sha384_sparc64_final(struct shash_desc *desc, u8 *hash)
 	sha512_sparc64_final(desc, D);
 
 	memcpy(hash, D, 48);
-	memset(D, 0, 64);
+	memzero_explicit(D, 64);
 
 	return 0;
 }

qlambert