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

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