[PATCH 5/8] dm: replace memset by memzero_explicit

From: Julia Lawall
Date: Sun Nov 30 2014 - 12:06:59 EST


From: Julia Lawall <julia@xxxxxxx>

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/)

// <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 <dborkman@xxxxxxxxxx>

Signed-off-by: Julia Lawall <julia@xxxxxxx>

---
Daniel Borkmann suggested that these patches could go through Herbert Xu's
cryptodev tree.

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;
}


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