On 4/13/20 5:31 PM, Joe Perches wrote:

On Mon, 2020-04-13 at 17:15 -0400, Waiman Long wrote:

quoted

Since kfree_sensitive() will do an implicit memzero_explicit(), there
is no need to call memzero_explicit() before it. Eliminate those
memzero_explicit() and simplify the call sites.

2 bits of trivia:

quoted

diff --git a/drivers/crypto/allwinner/sun8i-ce/sun8i-ce-cipher.c b/drivers/crypto/allwinner/sun8i-ce/sun8i-ce-cipher.c

[]

quoted

@@ -391,10 +388,7 @@ int sun8i_ce_aes_setkey(struct crypto_skcipher *tfm, const u8 *key,
 		dev_dbg(ce->dev, "ERROR: Invalid keylen %u\n", keylen);
 		return -EINVAL;
 	}
-	if (op->key) {
-		memzero_explicit(op->key, op->keylen);
-		kfree(op->key);
-	}
+	kfree_sensitive(op->key);
 	op->keylen = keylen;
 	op->key = kmemdup(key, keylen, GFP_KERNEL | GFP_DMA);
 	if (!op->key)

It might be a defect to set op->keylen before the kmemdup succeeds.

It could be. I can move it down after the op->key check.

quoted

@@ -416,10 +410,7 @@ int sun8i_ce_des3_setkey(struct crypto_skcipher *tfm, const u8 *key,
 	if (err)
 		return err;
 
-	if (op->key) {
-		memzero_explicit(op->key, op->keylen);
-		kfree(op->key);
-	}
+	free_sensitive(op->key, op->keylen);

Why not kfree_sensitive(op->key) ?

Oh, it is a bug. I will send out v2 to fix that.

Thanks for spotting it.

Cheers,
Longman