linux-kernel - Re: [KVM PATCH v3 2/2] kvm: add support for irqfd via eventfd-notification interface

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]

Date:	Sun, 3 May 2009 11:07:26 -0700 (PDT)
From:	Davide Libenzi <davidel@...ilserver.org>
To:	Al Viro <viro@...IV.linux.org.uk>
cc:	Gregory Haskins <ghaskins@...ell.com>, kvm@...r.kernel.org,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	avi@...hat.com
Subject: Re: [KVM PATCH v3 2/2] kvm: add support for irqfd via eventfd-notification
 interface

On Sun, 3 May 2009, Al Viro wrote:

> On Mon, Apr 27, 2009 at 02:33:34PM -0400, Gregory Haskins wrote:
> > +	/* We re-use eventfd for irqfd */
> > +	fd = sys_eventfd2(0, 0);
> > +	if (fd < 0) {
> > +		ret = fd;
> > +		goto fail;
> > +	}
> > +
> > +	/* We maintain a reference to eventfd for the irqfd lifetime */
> > +	file = eventfd_fget(fd);
> > +	if (IS_ERR(file)) {
> > +		ret = PTR_ERR(file);
> > +		goto fail;
> > +	}
> > +
> > +	irqfd->file = file;
> 
> This is just plain wrong.  You have no promise whatsoever that caller of
> that sucker won't race with e.g. dup2().  IOW, you can't assume that
> file will be of the expected kind.

The eventfd_fget() checks for the file_operations pointer, before 
returning the file*, and fails if the fd in not an eventfd. Or you have 
other concerns?



- Davide


--
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/