Re: [PATCH] rc: correctly handling failed allocation

From: Mauro Carvalho Chehab
Date: Thu Mar 03 2016 - 08:03:09 EST


Em Tue, 16 Feb 2016 10:54:54 +0000
Sean Young <sean@xxxxxxxx> escreveu:

> On Mon, Feb 15, 2016 at 09:33:11PM -0500, Insu Yun wrote:
> > Since rc_allocate_device() uses kmalloc,
> > it can returns NULL, so need to check,
> > otherwise, NULL derefenrece can be happened.
>
> Thanks for catching that.
>
> > Signed-off-by: Insu Yun <wuninsu@xxxxxxxxx>
> > ---
> > drivers/media/rc/igorplugusb.c | 3 +++
> > 1 file changed, 3 insertions(+)
> >
> > diff --git a/drivers/media/rc/igorplugusb.c b/drivers/media/rc/igorplugusb.c
> > index b36e515..df37cd5 100644
> > --- a/drivers/media/rc/igorplugusb.c
> > +++ b/drivers/media/rc/igorplugusb.c
> > @@ -191,6 +191,8 @@ static int igorplugusb_probe(struct usb_interface *intf,
> > usb_make_path(udev, ir->phys, sizeof(ir->phys));
> >
> > rc = rc_allocate_device();
> > + if (!rc)
> > + goto fail;
>
> At this point, ret is not initialized but will be used in the error path.

Also, it should be setting "ret", like like:

if (!rc) {
ret = -ENOMEM;
goto fail;
}



>
> > rc->input_name = DRIVER_DESC;
> > rc->input_phys = ir->phys;
> > usb_to_input_id(udev, &rc->input_id);
> > @@ -213,6 +215,7 @@ static int igorplugusb_probe(struct usb_interface *intf,
> > ir->rc = rc;
> > ret = rc_register_device(rc);
> > if (ret) {
>
> I'm not sure how common it is to goto into another nesting level for an
> error path.

I can't remember a single case where we do that. Putting fail at the
end is indeed the clearer way of handling it.

> Also I just noticed that the code is leaking the timer in
> the error path.
>
> It might be better to put the "fail:" at the end after the last return
> for the successful case, and have a goto to it after both
> rc_allocate_device() and rc_register_device() in case they fail.
>
> > +fail:
> > dev_err(&intf->dev, "failed to register rc device: %d", ret);
> > rc_free_device(rc);
> > usb_free_urb(ir->urb);
> > --
> > 1.9.1
>
> Thanks
> Sean
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--
Thanks,
Mauro