From mboxrd@z Thu Jan 1 00:00:00 1970 From: Josh Triplett Subject: Re: [PATCH] drivers/char/mem.c: Add /dev/ioports, supporting 16-bit and 32-bit ports Date: Sun, 11 May 2014 14:05:19 -0700 Message-ID: <20140511210514.GB6056@thin> References: <20140509191914.GA7286@jtriplet-mobl1> <20140510070742.GE6099@debjann.fritz.box> <20140510193246.GA12079@thin> <20140511125006.GA16197@debjann.fritz.box> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20140511125006.GA16197-7cfQGs147y6a6lf8Wg2v7Z5kstrrjoWp@public.gmane.org> Sender: linux-api-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Jann Horn Cc: Arnd Bergmann , Greg Kroah-Hartman , akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-api@vger.kernel.org On Sun, May 11, 2014 at 02:50:06PM +0200, Jann Horn wrote: > On Sat, May 10, 2014 at 12:32:46PM -0700, Josh Triplett wrote: > > 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. > > Yes, on x86. What about other architectures? That's a good point; on architectures that map I/O to memory, this device should check port+count rather than port. Is there a reliable #define that identifies architectures with that property, other than CONFIG_X86? - Josh Triplett