RE: [PATCH v2 1/2] kernel/sys: add PR_GET_TASK_SIZE option to prctl(2)

[David Laight]

From: Cyrill Gorcunov
> Sent: 03 May 2019 09:32
> On Thu, May 02, 2019 at 05:46:08PM -0400, Joel Savitz wrote:
> > > Won't be possible to use put_user here? Something like
> > >
> > > static int prctl_get_tasksize(unsigned long __user *uaddr)
> > > {
> > >         return put_user(TASK_SIZE, uaddr) ? -EFAULT : 0;
> > > }
> >
> > What would be the benefit of using put_user() over copy_to_user() in
> > this context?
> 
> It is a common pattern to use put_user with native types, where
> copy_to_user more biased for composed types transfer.

It also removes all the crappy code that checks whether the
kernel buffer is valid.

	David

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