[PATCH 8/8] wusb: replace memset by memzero_explicit

From: Julia Lawall
Date: Sun Nov 30 2014 - 12:07:20 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/usb/wusbcore/dev-sysfs.c | 2 +-
drivers/usb/wusbcore/security.c | 8 ++++----
2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/usb/wusbcore/dev-sysfs.c b/drivers/usb/wusbcore/dev-sysfs.c
index 1018345..415b140 100644
--- a/drivers/usb/wusbcore/dev-sysfs.c
+++ b/drivers/usb/wusbcore/dev-sysfs.c
@@ -101,7 +101,7 @@ static ssize_t wusb_ck_store(struct device *dev,
if (wusbhc == NULL)
return -ENODEV;
result = wusb_dev_4way_handshake(wusbhc, usb_dev->wusb_dev, &ck);
- memset(&ck, 0, sizeof(ck));
+ memzero_explicit(&ck, sizeof(ck));
wusbhc_put(wusbhc);
return result < 0 ? result : size;
}
diff --git a/drivers/usb/wusbcore/security.c b/drivers/usb/wusbcore/security.c
index cc74d66..b66faaf 100644
--- a/drivers/usb/wusbcore/security.c
+++ b/drivers/usb/wusbcore/security.c
@@ -522,10 +522,10 @@ error_hs3:
error_hs2:
error_hs1:
memset(hs, 0, 3*sizeof(hs[0]));
- memset(&keydvt_out, 0, sizeof(keydvt_out));
- memset(&keydvt_in, 0, sizeof(keydvt_in));
- memset(&ccm_n, 0, sizeof(ccm_n));
- memset(mic, 0, sizeof(mic));
+ memzero_explicit(&keydvt_out, sizeof(keydvt_out));
+ memzero_explicit(&keydvt_in, sizeof(keydvt_in));
+ memzero_explicit(&ccm_n, sizeof(ccm_n));
+ memzero_explicit(mic, sizeof(mic));
if (result < 0)
wusb_dev_set_encryption(usb_dev, 0);
error_dev_set_encryption:

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