From: Waiman Long <longman@redhat.com>
To: Christophe Leroy <christophe.leroy@c-s.fr>,
Andrew Morton <akpm@linux-foundation.org>,
David Howells <dhowells@redhat.com>,
Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
James Morris <jmorris@namei.org>,
"Serge E. Hallyn" <serge@hallyn.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Joe Perches <joe@perches.com>,
Matthew Wilcox <willy@infradead.org>,
David Rientjes <rientjes@google.com>
Cc: linux-mm@kvack.org, keyrings@vger.kernel.org,
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Subject: Re: [PATCH v2 2/2] crypto: Remove unnecessary memzero_explicit()
Date: Tue, 14 Apr 2020 12:24:36 -0400 [thread overview]
Message-ID: <e194a51f-a5e5-a557-c008-b08cac558572@redhat.com> (raw)
In-Reply-To: <eca85e0b-0af3-c43a-31e4-bd5c3f519798@c-s.fr>
On 4/14/20 2:08 AM, Christophe Leroy wrote:
>
>
> Le 14/04/2020 à 00:28, Waiman Long a écrit :
>> 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. For better correctness,
>> the setting of keylen is also moved down after the key pointer check.
>>
>> Signed-off-by: Waiman Long <longman@redhat.com>
>> ---
>> .../allwinner/sun8i-ce/sun8i-ce-cipher.c | 19 +++++-------------
>> .../allwinner/sun8i-ss/sun8i-ss-cipher.c | 20 +++++--------------
>> drivers/crypto/amlogic/amlogic-gxl-cipher.c | 12 +++--------
>> drivers/crypto/inside-secure/safexcel_hash.c | 3 +--
>> 4 files changed, 14 insertions(+), 40 deletions(-)
>>
>> diff --git a/drivers/crypto/allwinner/sun8i-ce/sun8i-ce-cipher.c
>> b/drivers/crypto/allwinner/sun8i-ce/sun8i-ce-cipher.c
>> index aa4e8fdc2b32..8358fac98719 100644
>> --- a/drivers/crypto/allwinner/sun8i-ce/sun8i-ce-cipher.c
>> +++ b/drivers/crypto/allwinner/sun8i-ce/sun8i-ce-cipher.c
>> @@ -366,10 +366,7 @@ void sun8i_ce_cipher_exit(struct crypto_tfm *tfm)
>> {
>> struct sun8i_cipher_tfm_ctx *op = crypto_tfm_ctx(tfm);
>> - if (op->key) {
>> - memzero_explicit(op->key, op->keylen);
>> - kfree(op->key);
>> - }
>> + kfree_sensitive(op->key);
>> crypto_free_sync_skcipher(op->fallback_tfm);
>> pm_runtime_put_sync_suspend(op->ce->dev);
>> }
>> @@ -391,14 +388,11 @@ 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);
>> - }
>> - op->keylen = keylen;
>> + kfree_sensitive(op->key);
>> op->key = kmemdup(key, keylen, GFP_KERNEL | GFP_DMA);
>> if (!op->key)
>> return -ENOMEM;
>> + op->keylen = keylen;
>
> Does it matter at all to ensure op->keylen is not set when of->key is
> NULL ? I'm not sure.
>
> But if it does, then op->keylen should be set to 0 when freeing op->key.
My thinking is that if memory allocation fails, we just don't touch
anything and return an error code. I will not explicitly set keylen to 0
in this case unless it is specified in the API documentation.
Cheers,
Longman
next prev parent reply other threads:[~2020-04-14 16:25 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-13 21:15 [PATCH 0/2] mm, treewide: Rename kzfree() to kfree_sensitive() Waiman Long
2020-04-13 21:15 ` [PATCH 1/2] " Waiman Long
2020-04-14 0:29 ` David Rientjes
2020-04-14 8:32 ` Jason A. Donenfeld
2020-04-14 9:01 ` Michal Hocko
2020-04-14 12:48 ` David Sterba
2020-04-14 18:26 ` Waiman Long
2020-04-15 5:01 ` Johannes Weiner
2020-06-15 18:07 ` Dan Carpenter
2020-06-15 18:39 ` Waiman Long
2020-04-13 21:15 ` [PATCH 2/2] crypto: Remove unnecessary memzero_explicit() Waiman Long
2020-04-13 21:31 ` Joe Perches
2020-04-13 21:52 ` Waiman Long
2020-04-13 22:28 ` [PATCH v2 " Waiman Long
2020-04-14 6:08 ` Christophe Leroy
2020-04-14 16:24 ` Waiman Long [this message]
2020-04-14 19:16 ` Michal Suchánek
2020-04-14 19:37 ` Waiman Long
2020-04-14 19:44 ` Joe Perches
2020-04-14 13:06 ` [PATCH 1/2] mm, treewide: Rename kzfree() to kfree_sensitive() David Howells
2020-04-14 19:29 ` [PATCH v2 3/3] btrfs: Use kfree() in btrfs_ioctl_get_subvol_info() Waiman Long
2020-04-14 20:02 ` [PATCH v3 2/3] crypto: Remove unnecessary memzero_explicit() Waiman Long
2020-04-16 9:06 ` Corentin Labbe
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