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From:   Ashish Kalra <eashishkalra@gmail.com>
Date:   Fri, 23 Apr 2021 20:56:19 +0530
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     Ashish Kalra <eashishkalra@gmail.com>,
        Abheek Dhawan <adawesomeguy222@gmail.com>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Romain Perier <romain.perier@gmail.com>,
        Waiman Long <longman@redhat.com>,
        Allen Pais <apais@linux.microsoft.com>,
        Ivan Safonov <insafonov@gmail.com>,
        linux-staging@lists.linux.dev, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] staging: wlan-ng: silence incorrect type in argument 1
 (different address spaces) warning
Message-ID: <20210423152619.GA2469@ashish-NUC8i5BEH>
References: <20210420090142.GA4086@ashish-NUC8i5BEH>
 <YIE3IffGcjrkz4ZE@kroah.com>
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On Thu, Apr 22, 2021 at 10:43:13AM +0200, Greg Kroah-Hartman wrote:
> On Tue, Apr 20, 2021 at 02:31:42PM +0530, Ashish Kalra wrote:
> > Upon running sparse, "warning: incorrect type in argument 1 (different address spaces)
> > is brought to notice for this file.let's add correct typecast to make it cleaner and
> > silence the Sparse warning.
> > 
> > Signed-off-by: Ashish Kalra <eashishkalra@gmail.com>
> > ---
> >  drivers/staging/wlan-ng/p80211netdev.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/staging/wlan-ng/p80211netdev.c b/drivers/staging/wlan-ng/p80211netdev.c
> > index 6f9666dc0277..70570e8a5ad2 100644
> > --- a/drivers/staging/wlan-ng/p80211netdev.c
> > +++ b/drivers/staging/wlan-ng/p80211netdev.c
> > @@ -569,7 +569,7 @@ static int p80211knetdev_do_ioctl(struct net_device *dev,
> >  		goto bail;
> >  	}
> >  
> > -	msgbuf = memdup_user(req->data, req->len);
> > +	msgbuf = memdup_user((void __user *)req->data, req->len);
> 
> Why isn't data being declared as a __user pointer to start with?  Why is
> the cast needed here?
> 
> This feels wrong as if it is papering over the real problem.
> 
> thanks,
> 
> greg k-h
Thanks for your inputs
variable data in structure p80211ioctl_req is used only inside this function and is 
already casted to void __user * for copy_to_user. Should it be changed 
to void __user from caadr_t inside p80211ioctl.h. it should be same at runtime

--- a/drivers/staging/wlan-ng/p80211ioctl.h
+++ b/drivers/staging/wlan-ng/p80211ioctl.h
@@ -81,7 +81,7 @@
 
 struct p80211ioctl_req {
        char name[WLAN_DEVNAMELEN_MAX];
-       caddr_t data;
+       void __user *data;

Does this looks ok to you and is there any other check possible if this is ok?

Regards
Ashish