Yeah, you are right, I misread that bit. Should I resend second patch?
Thanks,
Chengguang.
> 在 2018年2月5日，下午9:11，Ilya Dryomov <idryomov@xxxxxxxxx> 写道：
>
> On Mon, Feb 5, 2018 at 1:06 PM, Chengguang Xu <cgxu519@xxxxxxxxxx> wrote:
>>
>>
>> Thanks,
>> Chengguang.
>>
>>
>>
>>> 在 2018年2月5日，下午7:51，Ilya Dryomov <idryomov@xxxxxxxxx> 写道：
>>>
>>> On Sun, Feb 4, 2018 at 11:08 AM, Chengguang Xu <cgxu519@xxxxxxxxxx> wrote:
>>>> There are many reasons of failure from get_secret(),
>>>> so it's necessary to add a check before calling crypto_free_skcipher()
>>>> in case of NULL pointer dereference.
>>>>
>>>> Signed-off-by: Chengguang Xu <cgxu519@xxxxxxxxxx>
>>>> ---
>>>> net/ceph/crypto.c | 6 ++++--
>>>> 1 file changed, 4 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/net/ceph/crypto.c b/net/ceph/crypto.c
>>>> index bf9d079..bb1dc2d 100644
>>>> --- a/net/ceph/crypto.c
>>>> +++ b/net/ceph/crypto.c
>>>> @@ -136,8 +136,10 @@ void ceph_crypto_key_destroy(struct ceph_crypto_key *key)
>>>> if (key) {
>>>> kfree(key->key);
>>>> key->key = NULL;
>>>> - crypto_free_skcipher(key->tfm);
>>>> - key->tfm = NULL;
>>>> + if (key->tfm) {
>>>> + crypto_free_skcipher(key->tfm);
>>>> + key->tfm = NULL;
>>>> + }
>>>> }
>>>> }
>>>
>>> Hi Chengguang,
>>>
>>> crypto_free_skcipher() can handle a NULL pointer just fine:
>>>
>>> void crypto_destroy_tfm(void *mem, struct crypto_tfm *tfm)
>>> {
>>> struct crypto_alg *alg;
>>>
>>> if (unlikely(!mem))
>>> return;
>>
>> Hi Ilya,
>>
>> How about crypto_skcipher_tfm() in below call stack?
>>
>> ceph_crypto_key_destroy() -> crypto_free_skcipher() -> crypto_destroy_tfm() -> crypto_skcipher_tfm()
>>
>> static inline struct crypto_tfm *crypto_skcipher_tfm(
>> struct crypto_skcipher *tfm)
>> {
>> return &tfm->base;
>> }
>
> That's an address-of, not a dereference. When tfm is NULL, the result
> is the offset of base in crypto_skcipher.
>
> Thanks,
>
> Ilya
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