netdev - Re: [PATCH 1/4] net: usbnet: use usb_control_msg_recv() and usb_control_msg

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Date:   Wed, 23 Sep 2020 19:38:13 +0530
From:   Himadri Pandya <himadrispandya@...il.com>
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     David Miller <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Oliver Neukum <oneukum@...e.com>,
        pankaj.laxminarayan.bharadiya@...el.com,
        Kees Cook <keescook@...omium.org>, yuehaibing@...wei.com,
        petkan@...leusys.com, ogiannou@...il.com,
        USB list <linux-usb@...r.kernel.org>,
        netdev <netdev@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        linux-kernel-mentees@...ts.linuxfoundation.org
Subject: Re: [PATCH 1/4] net: usbnet: use usb_control_msg_recv() and usb_control_msg_send()

On Wed, Sep 23, 2020 at 3:54 PM Greg KH <gregkh@...uxfoundation.org> wrote:
>
> On Wed, Sep 23, 2020 at 02:35:16PM +0530, Himadri Pandya wrote:
> > Potential incorrect use of usb_control_msg() has resulted in new wrapper
> > functions to enforce its correct usage with proper error check. Hence
> > use these new wrapper functions instead of calling usb_control_msg()
> > directly.
> >
> > Signed-off-by: Himadri Pandya <himadrispandya@...il.com>
> > ---
> >  drivers/net/usb/usbnet.c | 46 ++++------------------------------------
> >  1 file changed, 4 insertions(+), 42 deletions(-)
> >
> > diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c
> > index 2b2a841cd938..a38a85bef46a 100644
> > --- a/drivers/net/usb/usbnet.c
> > +++ b/drivers/net/usb/usbnet.c
> > @@ -1982,64 +1982,26 @@ EXPORT_SYMBOL(usbnet_link_change);
> >  static int __usbnet_read_cmd(struct usbnet *dev, u8 cmd, u8 reqtype,
> >                            u16 value, u16 index, void *data, u16 size)
> >  {
> > -     void *buf = NULL;
> > -     int err = -ENOMEM;
> > -
> >       netdev_dbg(dev->net, "usbnet_read_cmd cmd=0x%02x reqtype=%02x"
> >                  " value=0x%04x index=0x%04x size=%d\n",
> >                  cmd, reqtype, value, index, size);
> >
> > -     if (size) {
> > -             buf = kmalloc(size, GFP_KERNEL);
> > -             if (!buf)
> > -                     goto out;
> > -     }
> > -
> > -     err = usb_control_msg(dev->udev, usb_rcvctrlpipe(dev->udev, 0),
> > -                           cmd, reqtype, value, index, buf, size,
> > +     return usb_control_msg_recv(dev->udev, 0,
> > +                           cmd, reqtype, value, index, data, size,
> >                             USB_CTRL_GET_TIMEOUT);
> > -     if (err > 0 && err <= size) {
> > -        if (data)
> > -            memcpy(data, buf, err);
> > -        else
> > -            netdev_dbg(dev->net,
> > -                "Huh? Data requested but thrown away.\n");
> > -    }
> > -     kfree(buf);
> > -out:
> > -     return err;
> >  }
>
> Now there is no real need for these wrapper functions at all, except for
> the debugging which I doubt anyone needs anymore.
>
> So how about just deleting these and calling the real function instead?
>

Yes, that would be a better thing to do.

Thanks,
Himadri

> thanks,
>
> greg k-h