The kernel needs to validate that the pointers it gets from userland are valid, otherwise this could lead to an exploit/panic among other things.
//Jonas On 7/27/07, Michael Galassi <[EMAIL PROTECTED]> wrote: > A few hours ago I wrote: > > copyin() is called by the system call code and returns > > efault after validating the address, before actually > > touching it. > > This is the traditional way of doing things but is clearly expensive > as validating a user address takes forever and a bit. Do we blindly > use whatever address is passed in and then add checking to the page > fault code to figure out if we should just return efault? This would > be a blatant example of optimizing the common case at small cost for > the error case which most people probably don't care about. > > -michael >
