Re: [Qemu-devel] [PATCH] crypto: afalg: fix a NULL pointer dereference

["Longpeng (Mike)" <longpeng2@huawei.com>]

On 2017/11/7 1:18, Stefan Hajnoczi wrote:

> On Mon, Nov 06, 2017 at 02:21:11PM +0800, Longpeng(Mike) wrote:
>> Test-crypto-hash calls qcrypto_hash_bytesv/digest/base64 with
>> errp=NULL, this will cause a NULL poniter deference if afalg_driver
>> doesn't support requested algos:
>>     ret = qcrypto_hash_afalg_driver.hash_bytesv(alg, iov, niov,
>>                                                 result, resultlen,
>>                                                 errp);
>>     if (ret == 0) {
>>         return ret;
>>     }
>>
>>     error_free(*errp);  // <--- here
>>
>> So we must check 'errp & *errp' before dereference.
> 
> Only errp needs to be checked.  It's okay to invoke error_free(NULL):
> 
>   void error_free(Error *err)
>   {
>       if (err) {


Ah yes, thanks for your note :)

I'll pick another approach to fix this bug.

-- 
Regards,
Longpeng(Mike)