linux-kernel - Re: [PATCH] regression: vmalloc easily fail.

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: <20081104175111.GA27481@poweredge.glommer>
Date:	Tue, 4 Nov 2008 15:51:11 -0200
From:	Glauber Costa <glommer@...hat.com>
To:	Nick Piggin <npiggin@...e.de>
Cc:	Avi Kivity <avi@...hat.com>, linux-kernel@...r.kernel.org,
	kvm@...r.kernel.org, aliguori@...emonkey.ws,
	Jeremy Fitzhardinge <jeremy@...p.org>,
	Krzysztof Helt <krzysztof.h1@...zta.fm>
Subject: Re: [PATCH] regression: vmalloc easily fail.

On Fri, Oct 31, 2008 at 08:16:44AM +0100, Nick Piggin wrote:
> On Thu, Oct 30, 2008 at 09:28:54AM -0200, Glauber Costa wrote:
> > On Thu, Oct 30, 2008 at 05:49:41AM +0100, Nick Piggin wrote:
> > > On Wed, Oct 29, 2008 at 08:07:37PM -0200, Glauber Costa wrote:
> > > > On Wed, Oct 29, 2008 at 11:43:33AM +0100, Nick Piggin wrote:
> > > > > On Wed, Oct 29, 2008 at 12:29:40PM +0200, Avi Kivity wrote:
> > > > > > Nick Piggin wrote:
> > > > > > >Hmm, spanning <30MB of memory... how much vmalloc space do you have?
> > > > > > >
> > > > > > >  
> > > > > > 
> > > > > > From the original report:
> > > > > > 
> > > > > > >VmallocTotal:     122880 kB
> > > > > > >VmallocUsed:       15184 kB
> > > > > > >VmallocChunk:      83764 kB
> > > > > > 
> > > > > > So it seems there's quite a bit of free space.
> > > > > > 
> > > > > > Chunk is the largest free contiguous region, right?  If so, it seems the 
> > > > > 
> > > > > Yes.
> > > > > 
> > > > > 
> > > > > > problem is unrelated to guard pages, instead the search isn't finding a 
> > > > > > 1-page area (with two guard pages) for some reason, even though lots of 
> > > > > > free space is available.
> > > > > 
> > > > > Hmm. The free area search could be buggy...
> > > > Do you want me to grab any specific info of it? Or should I just hack myself
> > > > randomly into it? I'll probably have some time for that tomorrow.
> > > 
> > > I took a bit of a look. Does this help you at all?
> > > 
> > > I still think we should get rid of the guard pages in non-debug kernels
> > > completely, but hopefully this will fix your problems?
> > unfortunately, it doesn't.
> > problem still happen in a kernel with this patch.
> 
> That's weird. Any chance you could dump a list of all the vmap area start
> and end adresses and their flags before returning failure?

by the way, a slightly modified version of your patch, without this snippet:

@@ -362,7 +363,7 @@ retry:
                                goto found;
                }

-               while (addr + size >= first->va_start && addr + size <= vend) {
+               while (addr + size > first->va_start && addr + size <= vend) {
                        addr = ALIGN(first->va_end + PAGE_SIZE, align);

                        n = rb_next(&first->rb_node);


WFM nicely so far.

I'm attaching /proc/vmallocinfo during kvm execution


View attachment "vmalloc.works" of type "text/plain" (11043 bytes)