Re: [PATCH] staging: comedi: remove __user annotation inside of struct's

[Ian Abbott]

On 2012-05-09 00:55, H Hartley Sweeten wrote:
> On Tuesday, May 08, 2012 4:41 PM, H Hartley Sweeten wrote:
> > The structs' comedi_insn, coomedi_insnlist, comedi_cmd,
> > comedi_chaninfo, and comedi_rangeinfo are all passed to
> > the kernel from user space using ioctl commands. They
> > are then copied to kernel space using copy_from_user()
> > before the data is passed to the drivers.
> >
> > The __user annotation should not be used with variables
> > inside the struct. This produces a lot of sparse warnings
> > like:
> >
> > warning: dereference of noderef expression
> >
> > Signed-off-by: H Hartley Sweeten<hsweeten@xxxxxxxxxxxxxxxxxxx>
> > Cc: Ian Abbott<abbotti@xxxxxxxxx>
> > Cc: Mori Hess<fmhess@xxxxxxxxxxxxxxxxxxxxx>
> > Cc: Greg Kroah-Hartman<gregkh@xxxxxxxxxxxxxxxxxxx>
> >
> > ---
> >
> > Note: This patch exposes some new warnings about different
> > address space. These will be addressed.
>
> Please ignore this patch.
>
> It appears the annotations in the struct definitions are correct.

Personally, I think you were on the mark with the patch.  It's better to 
avoid using __user in comedi.h so it can be used as-is in user-space. 
All of the structures in comedi.h are used in user-space (although 
Comedilib uses its own version of comedi.h without all the typedef 
eliminations that have been done in "staging") and some of them are also 
deep-copied into kernel-space objects of the same type, where the 
pointers in the structs would no longer be user-space pointers.

--
-=( Ian Abbott @ MEV Ltd.    E-mail: <abbotti@xxxxxxxxx>        )=-
-=( Tel: +44 (0)161 477 1898   FAX: +44 (0)161 718 3587         )=-
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