[PATCH 3.16.y-ckt 069/216] dm crypt: use memzero_explicit for on-stack buffer

[Luis Henriques]

3.16.7-ckt4 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Milan Broz <gmazyland at gmail.com>

commit 1a71d6ffe18c0d0f03fc8531949cc8ed41d702ee upstream.

Use memzero_explicit to cleanup sensitive data allocated on stack
to prevent the compiler from optimizing and removing memset() calls.

Signed-off-by: Milan Broz <gmazyland at gmail.com>
Signed-off-by: Mike Snitzer <snitzer at redhat.com>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 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 3e6ef4b1fb46..f87223056696 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -709,7 +709,7 @@ 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;
 }
 
-- 
2.1.4