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From:   B K Karthik <bkkarthik@pesu.pes.edu>
Date:   Wed, 15 Jul 2020 07:34:53 -0400
Message-ID: <CAAhDqq0NYcX+UJi+GfbLP7q-MqrXfDaoB5z64GmgO3L7zpCMjQ@mail.gmail.com>
Subject: Re: [PATCH] staging: comedi: comedi_fops.c: changed type in
 assignment to unsigned int *
To:     Ian Abbott <abbotti@mev.co.uk>
Cc:     H Hartley Sweeten <hsweeten@visionengravers.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Al Viro <viro@zeniv.linux.org.uk>,
        Xiyu Yang <xiyuyang19@fudan.edu.cn>,
        Michel Lespinasse <walken@google.com>,
        Divyansh Kamboj <kambojdivyansh2000@gmail.com>,
        devel@driverdev.osuosl.org, linux-kernel@vger.kernel.org
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On Wed, Jul 15, 2020 at 7:19 AM Ian Abbott <abbotti@mev.co.uk> wrote:
>
> On 15/07/2020 05:48, B K Karthik wrote:
> > fixed a sparse warning by changing the type in
> > assignment from void [noderef] __user * to unsigned int *
> > (different address space)
> >
> > Signed-off-by: B K Karthik <karthik.bk2000@live.com>
> > ---
> >   drivers/staging/comedi/comedi_fops.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/staging/comedi/comedi_fops.c b/drivers/staging/comedi/comedi_fops.c
> > index 3f70e5dfac39..4cc012e231b7 100644
> > --- a/drivers/staging/comedi/comedi_fops.c
> > +++ b/drivers/staging/comedi/comedi_fops.c
> > @@ -2956,7 +2956,7 @@ static int get_compat_cmd(struct comedi_cmd *cmd,
> >       cmd->scan_end_arg = v32.scan_end_arg;
> >       cmd->stop_src = v32.stop_src;
> >       cmd->stop_arg = v32.stop_arg;
> > -     cmd->chanlist = compat_ptr(v32.chanlist);
> > +     cmd->chanlist = (unsigned int *) compat_ptr(v32.chanlist);
>
> That should be:
>
>         cmd->chanlist = (unsigned int __force *)compat_ptr(v32.chanlist);
>
> >       cmd->chanlist_len = v32.chanlist_len;
> >       cmd->data = compat_ptr(v32.data);
> >       cmd->data_len = v32.data_len;
> >
>
> A reverse cast is required in put_compat_cmd():
>
>         v32.chanlist = ptr_to_compat((unsigned int __user *)cmd->chanlist);
>
> Those changes will get rid of the sparse warnings.

Thank you for the clarifications Ian. I will make the changes and submit a patch

thanks,

karthik