Re: [RFC][2.5] generic_usercopy() function (resend, forgot the patches)

[David Wagner]

Michael Hunold  wrote:
> /*
>- * helper function -- handles userspace copying for ioctl arguments
>- */
>-int
>-video_usercopy(struct inode *inode, struct file *file,
>-	       unsigned int cmd, unsigned long arg,
>-	       int (*func)(struct inode *inode, struct file *file,
>-			   unsigned int cmd, void *arg))
>-{
...
>-		if (copy_from_user(parg, (void *)arg, _IOC_SIZE(cmd)))
...
>-	err = func(inode, file, cmd, parg);
...

What about doubly-indirected pointers?  i.e., arg is a pointer
to a structure that itself contains a pointer?  Can this happen?