linux-kernel - Re: [PATCH -next] mISDN: hfcsusb: Fix potential NULL pointer dereference

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Message-ID: <b565e6fa-a52f-f4f1-21b9-c63332d06ea0@huawei.com>
Date:   Thu, 31 Jan 2019 17:41:46 +0800
From:   YueHaibing <yuehaibing@...wei.com>
To:     David Miller <davem@...emloft.net>
CC:     <isdn@...ux-pingi.de>, <gustavo@...eddedor.com>,
        <bigeasy@...utronix.de>, <linux-kernel@...r.kernel.org>,
        <netdev@...r.kernel.org>
Subject: Re: [PATCH -next] mISDN: hfcsusb: Fix potential NULL pointer
 dereference

On 2019/1/31 2:10, David Miller wrote:
> From: YueHaibing <yuehaibing@...wei.com>
> Date: Wed, 30 Jan 2019 18:19:02 +0800
> 
>> There is a potential NULL pointer dereference in case
>> kzalloc() fails and returns NULL.
>>
>> Fixes: 69f52adb2d53 ("mISDN: Add HFC USB driver")
>> Signed-off-by: YueHaibing <yuehaibing@...wei.com>
>> ---
>>  drivers/isdn/hardware/mISDN/hfcsusb.c | 2 ++
>>  1 file changed, 2 insertions(+)
>>
>> diff --git a/drivers/isdn/hardware/mISDN/hfcsusb.c b/drivers/isdn/hardware/mISDN/hfcsusb.c
>> index 124ff53..5660d5a 100644
>> --- a/drivers/isdn/hardware/mISDN/hfcsusb.c
>> +++ b/drivers/isdn/hardware/mISDN/hfcsusb.c
>> @@ -263,6 +263,8 @@ hfcsusb_ph_info(struct hfcsusb *hw)
>>  	int i;
>>  
>>  	phi = kzalloc(struct_size(phi, bch, dch->dev.nrbchan), GFP_ATOMIC);
>> +	if (!phi)
>> +		return;
> 
> If we fail with an error and do not perform the operation we were requested to
> make, we must return an error to the caller, and the caller must do something
> reasonable with that error (perhaps return it to it's caller) and so on and
> so forth.


hfcsusb_ph_info alloced the 'phi'，then use it _alloc_mISDN_skb in _queue_data.
while _alloc_mISDN_skb fails, it also just return without err handling,then kfree(phi).
It seems that all the caller of hfcsusb_ph_info doesn't care the return value.

> 
> .
>