From: Julia Lawall Subject: [PATCH 2/8] sparc64: replace memset by memzero_explicit Date: Sun, 30 Nov 2014 17:59:28 +0100 Message-ID: <1417366774-32412-3-git-send-email-Julia.Lawall@lip6.fr> References: <1417366774-32412-1-git-send-email-Julia.Lawall@lip6.fr> Cc: dborkman@redhat.com, herbert@gondor.apana.org.au, kernel-janitors@vger.kernel.org, "David S. Miller" , linux-crypto@vger.kernel.org, sparclinux@vger.kernel.org, linux-kernel@vger.kernel.org, Julia Lawall To: Herbert Xu Return-path: In-Reply-To: <1417366774-32412-1-git-send-email-Julia.Lawall@lip6.fr> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-crypto.vger.kernel.org From: Julia Lawall 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 --- Daniel Borkmann suggested that these patches could go through Herbert Xu's cryptodev tree. I was not able to compile test these. 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/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; } 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; }