Re: [PATCH] drivers/char/mem.c: Add /dev/ioports, supporting 16-bit and 32-bit ports

Josh Triplett
2014-05-10T19:32:46Z

On Sat, May 10, 2014 at 09:07:42AM +0200, Jann Horn wrote:
> On Fri, May 09, 2014 at 12:19:16PM -0700, Josh Triplett wrote:
> > + if (port > 65535)
> > + return 0;
> > + switch (count) {
> [...]
> > + case 4:
> > + if (__put_user(inl(port), buf) < 0)
> > + return -EFAULT;
>
> What if I attempt a four-byte read at 65535? That would access four
> out-of-bounds bytes, right?

No, it would do an ind instruction on port 65535.

- Josh Triplett