From: Julia Lawall Subject: [PATCH 7/8] crypto: replace memset by memzero_explicit Date: Sun, 30 Nov 2014 17:59:33 +0100 Message-ID: <1417366774-32412-8-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" , Russell King , linux-crypto@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Julia Lawall To: Herbert Xu Return-path: Received: from mail3-relais-sop.national.inria.fr ([192.134.164.104]:6030 "EHLO mail3-relais-sop.national.inria.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752163AbaK3RF3 (ORCPT ); Sun, 30 Nov 2014 12:05:29 -0500 In-Reply-To: <1417366774-32412-1-git-send-email-Julia.Lawall@lip6.fr> Sender: linux-crypto-owner@vger.kernel.org List-ID: 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 this one. 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; }