linux-kernel - Re: [PATCH -next] drivers: w1: use kfree

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Message-ID: <16959408-3e91-774d-484f-508caff1f8f7@huawei.com>
Date:   Tue, 17 May 2022 21:03:43 +0800
From:   Yang Yingliang <yangyingliang@...wei.com>
To:     Greg KH <gregkh@...uxfoundation.org>
CC:     <linux-kernel@...r.kernel.org>, <linux-hwmon@...r.kernel.org>,
        <zbr@...emap.net>, <jdelvare@...e.com>, <linux@...ck-us.net>
Subject: Re: [PATCH -next] drivers: w1: use kfree_sensitive()


On 2022/5/17 18:18, Greg KH wrote:
> On Wed, May 11, 2022 at 03:25:52PM +0800, Yang Yingliang wrote:
>> Hi,
>>
>> On 2022/5/11 14:45, Greg KH wrote:
>>> On Wed, May 11, 2022 at 02:49:54PM +0800, Yang Yingliang wrote:
>>>> Use kfree_sensitive() instead of open-coding it.
>>>>
>>>> Signed-off-by: Yang Yingliang <yangyingliang@...wei.com>
>>>> ---
>>>>    drivers/w1/w1.c | 3 +--
>>>>    1 file changed, 1 insertion(+), 2 deletions(-)
>>>>
>>>> diff --git a/drivers/w1/w1.c b/drivers/w1/w1.c
>>>> index f2ae2e563dc5..a0a6c3c739d9 100644
>>>> --- a/drivers/w1/w1.c
>>>> +++ b/drivers/w1/w1.c
>>>> @@ -73,8 +73,7 @@ static void w1_master_release(struct device *dev)
>>>>    	struct w1_master *md = dev_to_w1_master(dev);
>>>>    	dev_dbg(dev, "%s: Releasing %s.\n", __func__, md->name);
>>>> -	memset(md, 0, sizeof(struct w1_master) + sizeof(struct w1_bus_master));
>>>> -	kfree(md);
>>>> +	kfree_sensitive(md);
>>> Does this actually change anything?  Why is the memset being called here
>>> at all?
>> It's no functional change and I got this by
>> scripts/coccinelle/api/kfree_sensitive.cocci.
>> I'm not sure why using memset() here.
> I think the memset() can just be dropped.  Can you make that change and
> test it to verify it still works properly with that change?
I can make change and send a patch for this, but I don't have device to 
test it.
>
> thanks,
>
> greg k-h
> .