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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20140511210514.GB6056@thin>
Date:	Sun, 11 May 2014 14:05:19 -0700
From:	Josh Triplett <josh@...htriplett.org>
To:	Jann Horn <jann@...jh.net>
Cc:	Arnd Bergmann <arnd@...db.de>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
	linux-api@...r.kernel.org
Subject: Re: [PATCH] drivers/char/mem.c: Add /dev/ioports, supporting 16-bit
 and 32-bit ports

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
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/