linux-kernel - Re: [PATCH 2/2] crypto: chcr

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Date:   Thu, 13 Apr 2017 18:38:55 +0200
From:   Christophe JAILLET <christophe.jaillet@...adoo.fr>
To:     Dan Carpenter <dan.carpenter@...cle.com>,
        Harsh Jain <harshjain.prof@...il.com>
Cc:     Herbert Xu <herbert@...dor.apana.org.au>, davem@...emloft.net,
        harsh@...lsio.com, hariprasad@...lsio.com,
        linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org,
        kernel-janitors@...r.kernel.org
Subject: Re: [PATCH 2/2] crypto: chcr - Fix error checking

Le 13/04/2017 à 18:13, Dan Carpenter a écrit :
> On Thu, Apr 13, 2017 at 08:37:50PM +0530, Harsh Jain wrote:
>> On Thu, Apr 13, 2017 at 8:20 PM, Christophe JAILLET
>> <christophe.jaillet@...adoo.fr> wrote:
>>> Le 13/04/2017 à 16:04, Dan Carpenter a écrit :
>>>> On Thu, Apr 13, 2017 at 02:14:30PM +0200, Christophe JAILLET wrote:
>>>>> If 'chcr_alloc_shash()' a few lines above fails, 'base_hash' can be an
>>>>> error pointer when we 'goto out'.
>>>>> So checking for NULL here is not enough because it is likely that
>>>>> 'chcr_free_shash' will crash if we pass an error pointer.
>>>>>
>>>>> Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
>>>>> ---
>>>>> Another solution, amybe safer, would be to instrument 'chcr_free_shash'
>>>>> or
>>>>> 'crypto_free_shash' to accept an error pointer and return immediatelly in
>>>>> such a case.
>>>>> ---
>>>>>    drivers/crypto/chelsio/chcr_algo.c | 2 +-
>>>>>    1 file changed, 1 insertion(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/drivers/crypto/chelsio/chcr_algo.c
>>>>> b/drivers/crypto/chelsio/chcr_algo.c
>>>>> index f19590ac8775..41750b97f43c 100644
>>>>> --- a/drivers/crypto/chelsio/chcr_algo.c
>>>>> +++ b/drivers/crypto/chelsio/chcr_algo.c
>>>>> @@ -2351,7 +2351,7 @@ static int chcr_authenc_setkey(struct crypto_aead
>>>>> *authenc, const u8 *key,
>>>>>          }
>>>>>    out:
>>>>>          aeadctx->enckey_len = 0;
>>>>> -       if (base_hash)
>>>>> +       if (!IS_ERR_OR_NULL(base_hash))
>>>>>                  chcr_free_shash(base_hash);
>>>> Ah...  Ok.  Fine, but redo the first patch anyway because it shouldn't
>>>> ever be NULL.
>>>>
>>>> regards,
>>>> dan carpenter
>>> Hi Dan,
>>>
>>> I will update the first patch as you proposed in order to:
>>>     - teach 'chcr_alloc_shash' not to return NULL
>>>     - initialize 'base_hash' with ERR_PTR(-EINVAL)
>>>     - update the above test to !IS_ERR.
>>> The 2 patches will be merged in only 1.
>>>
>>> Thanks for your suggestions.
>> Thanks for pointing the error. or You can simply return instead of
>> goto. Just like that.
>>
>>       1.3 @@ -2455,7 +2455,8 @@ static int chcr_authenc_setkey(struct cr
>>       1.4   base_hash  = chcr_alloc_shash(max_authsize);
>>       1.5   if (IS_ERR(base_hash)) {
>>       1.6   pr_err("chcr : Base driver cannot be loaded\n");
>>       1.7 - goto out;
>>       1.8 + aeadctx->enckey_len = 0;
>>       1.9 + return -EINVAL;
> Don't do that.  There should be a goto.
>
> regards,
> dan carpenter
>
>
Agreed.

Having direct return after some other gotos statement puzzles my 
coccinelle scripts and are spurious (at least IMHO).

best regards,
CJ