Re: [PATCH 5/8 v2] dm: replace memset by memzero_explicit
From: Milan Broz <hidden>
Date: 2014-12-01 21:04:03
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dm-devel, kernel-janitors, lkml
On 11/30/2014 06:03 PM, Julia Lawall wrote:
From: Julia Lawall <redacted> 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/)
Ack, but I submitted the same patch a week ago.... https://www.redhat.com/archives/dm-devel/2014-November/msg00084.html Mike, please could you add this to linux-next tree or you want this to go through Herbert's tree? (I do not think it is good idea for DM patches.) Thanks, Milan
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// <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 [off-list ref] Signed-off-by: Julia Lawall <redacted> --- 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; }