On Fri, Feb 22, 2013 at 12:16:58PM -0800, Andi Kleen wrote: > ville.syrjala at linux.intel.com writes: > > > From: Ville Syrj?l? <ville.syrjala at linux.intel.com> > > > > to_user_ptr() simply casts a pointer passed as u64 from user space > > to void __user * correctly. Using this lets us get rid of all the > > tiresome casts. > > The whole point of __user is to track it elsewhere to avoid mistakes, > which may result in security bugs. > > A __user cast usually means your tracking is not complete, it's > supposed to be ugly so that you fix the tracking. Prettying > it defeats that point. > > How about just changing the original field to a pointer and add > the __user there? That would introduce 32bit vs. 64bit issues. We pass all user space pointer as __u64 precisely to avoid such issues. -- Ville Syrj?l? Intel OTC
