linux-kernel - Re: [PATCH] HID: lg: fix noderef.cocci warnings

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Date:   Wed, 23 Nov 2016 08:03:51 +0100 (CET)
From:   Julia Lawall <julia.lawall@...6.fr>
To:     Fengguang Wu <lkp@...el.com>
cc:     Jiri Kosina <jikos@...nel.org>,
        Benjamin Tissoires <benjamin.tissoires@...hat.com>,
        kbuild-all@...org, linux-input@...r.kernel.org,
        linux-kernel@...r.kernel.org, Gilles Muller <Gilles.Muller@...6.fr>
Subject: Re: [PATCH] HID: lg: fix noderef.cocci warnings



On Wed, 23 Nov 2016, Fengguang Wu wrote:

> On Tue, Nov 22, 2016 at 11:44:34AM +0100, Jiri Kosina wrote:
> > On Mon, 21 Nov 2016, Benjamin Tissoires wrote:
> >
> > > > Generated by: scripts/coccinelle/misc/noderef.cocci
> > > >
> > > > CC: Benjamin Tissoires <benjamin.tissoires@...hat.com>
> > > > Signed-off-by: Fengguang Wu <fengguang.wu@...el.com>
> > > > ---
> > > >
> > > >  hid-lg.c |    6 ++++--
> > > >  1 file changed, 4 insertions(+), 2 deletions(-)
> > > >
> > > > --- a/drivers/hid/hid-lg.c
> > > > +++ b/drivers/hid/hid-lg.c
> > > > @@ -777,8 +777,10 @@ static int lg_probe(struct hid_device *h
> > > >  			buf[1] = 0xB2;
> > > >  			get_random_bytes(&buf[2], 2);
> > > >
> > > > -			ret = hid_hw_raw_request(hdev, buf[0], buf,
> > > sizeof(buf),
> > > > -					HID_FEATURE_REPORT,
> > > HID_REQ_SET_REPORT);
> > > > +			ret = hid_hw_raw_request(hdev, buf[0], buf,
> > > > +						 sizeof(*buf),
> > >
> > > This is wrong. I messed up and should have used "sizeof(cbuf)", but the
> > > coccinelle script failed at detecting the correct solution (I guess it
> > > couldn't).
> >
> > Fengguang, is there anything that could be done to improve this?
>
> CC Julie and Gilles. I'm not sure if the coccinelle script could be
> made that smart. :)

Thanks for forwarding.  From looking at the code snippet, I have the
impression that if it were possible, it would require an interprocedural
analysis, and the cost would outweigh the benefit.  Basically, I don't see
any cbuf nearby.

julia


> > > Jiri, do you want me to send a v2 of the series or will you just amend
> > > the patch while applying?
> >
> > I'll fix that up, no worries. Thanks,
> >
> > --
> > Jiri Kosina
> > SUSE Labs
>