Re: [PATCH] staging: wlan-ng: silence incorrect type in argument 1 (different address spaces) warning

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Tue, Apr 27, 2021 at 05:53:30PM +0530, ashish wrote:
> On Sat, Apr 24, 2021 at 10:28:27AM +0200, Greg Kroah-Hartman wrote:
> > On Sat, Apr 24, 2021 at 01:45:29PM +0530, Ashish Kalra wrote:
> > > On Fri, Apr 23, 2021 at 11:11:05PM -0700, Joe Perches wrote:
> > > > On Sat, 2021-04-24 at 08:00 +0200, Greg Kroah-Hartman wrote:
> > > > > On Fri, Apr 23, 2021 at 08:56:19PM +0530, Ashish Kalra wrote:
> > > > > > 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.
> > > > []
> > > > > >  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?
> > > > > 
> > > > > Wait, what is "caddr_t"?  Try unwinding that mess first...
> > > > 
> > > > Might not be that simple.
> > > > 
> > > > include/linux/types.h:typedef __kernel_caddr_t  caddr_t;
> > > > include/uapi/linux/coda.h:typedef void * caddr_t;
> > > > include/uapi/asm-generic/posix_types.h:typedef char *           __kernel_caddr_t;
> > > > 
> > > > 
> > > data is part of p80211ioctl_req and is used at two places only inside p80211knetdev_do_ioctl
> > > it seems both places it will be used as void __user* only
> > > 
> > > 	msgbuf = memdup_user(req->data, req->len);
> > >         
> > > 	if (result == 0) {
> > >                 if (copy_to_user
> > >                     ((void __user *)req->data, msgbuf, req->len)) {
> > >                         result = -EFAULT;
> > >                 }
> > >         }
> > > 
> > > Will it still be problem if we change it from char * to void *.?
> > 
> > Why do you want to change it to void *?  Never use a void * unless it
> > has to point to unknown data.  That does not seem the case here.
> > 
> > > is there any way to check how caller of this function will be using it?
> > 
> > Look at the code to determine this...
> > 
> > thanks,
> > 
> > greg k-h
> Thanks Greg and Joe
> I have found that adding __user to data is also fixing this warning, 
> It should be fine logically to make this change
> Please share your opinion and will post v2 for this patch
> 
> --- 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;
> +       char __user *data;
>         u32 magic;
>         u16 len;
>         u32 result;
> -- 
> 2.30.2
> 
> 
> 

What do you think, try it and see and if you think it is correct, please
submit that change.  Don't wait for us...

thanks,

greg k-h