linux-kernel - Re: [PATCH] xen: hypercall: fix out-of-bounds memcpy

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:   Fri, 2 Feb 2018 19:34:01 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Juergen Gross <jgross@...e.com>,
        Nicolas Pitre <nico@...aro.org>,
        Andi Kleen <ak@...ux.intel.com>,
        Jan Beulich <jbeulich@...e.com>,
        xen-devel <xen-devel@...ts.xenproject.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] xen: hypercall: fix out-of-bounds memcpy

On Fri, Feb 02, 2018 at 05:11:02PM +0100, Arnd Bergmann wrote:
> On Fri, Feb 2, 2018 at 4:53 PM, Dan Carpenter <dan.carpenter@...cle.com> wrote:
> > On Fri, Feb 02, 2018 at 04:32:31PM +0100, Arnd Bergmann wrote:
> >>       switch (cmd) {
> >> +     case EVTCHNOP_bind_interdomain:
> >> +             len = sizeof(struct evtchn_bind_interdomain);
> >> +             break;
> >
> > This was in the original code, but I'm slightly surpprised that we're
> > using a switch statement here instead of a table.  I would have thought
> > this is a fast path but I don't know xen at all.
> 
> I thought about using a table, but figured the switch statement
> had a lower risk of getting something slightly wrong during the
> conversion.
> 
> I would expect gcc to turn this into a table lookup, since all the
> constants are consecutive, but it should not really matter since
> this is only the fallback path for ancient Xen releases. When Xen
> guest support was first merged in 2007, it was already
> deprecated.
> 

Ah.  Ok.  That makes sense.

regards,
dan carpenter