From mboxrd@z Thu Jan 1 00:00:00 1970 From: Julia Lawall Subject: [PATCH 5/8 v2] dm: replace memset by memzero_explicit Date: Sun, 30 Nov 2014 18:03:46 +0100 Message-ID: <1417367029-32762-6-git-send-email-Julia.Lawall@lip6.fr> References: <1417367029-32762-1-git-send-email-Julia.Lawall@lip6.fr> Return-path: In-Reply-To: <1417367029-32762-1-git-send-email-Julia.Lawall@lip6.fr> Sender: linux-kernel-owner@vger.kernel.org To: Alasdair Kergon Cc: kernel-janitors@vger.kernel.org, Mike Snitzer , dm-devel@redhat.com, Neil Brown , linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org List-Id: linux-raid.ids 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. v2: fixed email address drivers/md/dm-crypt.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c index fc93b93..08981be 100644 --- a/drivers/md/dm-crypt.c +++ b/drivers/md/dm-crypt.c @@ -705,7 +705,7 @@ static int crypt_iv_tcw_whitening(struct crypt_config *cc, for (i = 0; i < ((1 << SECTOR_SHIFT) / 8); i++) crypto_xor(data + i * 8, buf, 8); out: - memset(buf, 0, sizeof(buf)); + memzero_explicit(buf, sizeof(buf)); return r; }