linux-kernel - Re: [PATCH v3 2/2] usb: gadget: clear related members when goto fail

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Message-ID: <Yc8odYb41iNuQ16J@rowland.harvard.edu>
Date:   Fri, 31 Dec 2021 10:57:41 -0500
From:   Alan Stern <stern@...land.harvard.edu>
To:     Hangyu Hua <hbh25y@...il.com>
Cc:     balbi@...nel.org, gregkh@...uxfoundation.org, axboe@...nel.dk,
        jj251510319013@...il.com, dan.carpenter@...cle.com,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 2/2] usb: gadget: clear related members when goto fail

On Fri, Dec 31, 2021 at 10:31:51AM +0800, Hangyu Hua wrote:
> On 2021/12/31 上午3:46, Alan Stern wrote:

> >> @@ -1892,7 +1895,12 @@ dev_config (struct file *fd, const char __user *buf, size_t len, loff_t *ptr)
> >>      }
> >>      return value;
> >>
> >> +fail2:
> >> +    dev->dev = NULL;
> >> +fail1:
> >> +    dev->hs_config = NULL;
> >
> > It is not necessary to have all these different statement labels.  You
> > can simply have "fail:" clear all three pointers.

> I don't think so. It is not necessary to clean all three pointers if
> some of them aren't kbuf. I think it may be better to keep their own
> pointers.

If the pointers aren't set to a region inside kbuf then they are 
meaningless.  There is no reason to keep the old values.  It is better 
to avoid multiple unnecessary statement labels.

Alan Stern