From: Andrew Morton <akpm@linux-foundation.org>
To: Dave Jones <davej@redhat.com>
Cc: Joe Perches <joe@perches.com>, Dave Chinner <david@fromorbit.com>,
viro@zeniv.linux.org.uk,
Linux Kernel <linux-kernel@vger.kernel.org>,
David Rientjes <rientjes@google.com>
Subject: Re: suppress page allocation failure warnings from sys_listxattr
Date: Wed, 28 Mar 2012 19:28:04 -0700 [thread overview]
Message-ID: <20120328192804.7326bce9.akpm@linux-foundation.org> (raw)
In-Reply-To: <20120329020820.GB22697@redhat.com>
On Wed, 28 Mar 2012 22:08:20 -0400 Dave Jones <davej@redhat.com> wrote:
> On Wed, Mar 28, 2012 at 07:02:11PM -0700, Andrew Morton wrote:
>
> > > Also, what happens if something allocates
> > > and sits on a bunch of vmalloc'd memory ? would we start seeing oom kills ?
> >
> > vmalloc() would fail.
>
> Ok, that's a pretty boring failure mode, so not a big deal probably.
>
> > > (thinking of the context of my fuzzing tool where a bunch of instances could
> > > feasibly call these syscalls and not sit on huge amounts per thread, but
> > > collectively... I'm wondering if it could be provoked into killing
> > > processes I don't own)
> >
> > umm, if you wanted to deliberately trigger a vmalloc() failure then I
> > guess a good approach would be to locate a vmalloc() site which can
> > persist beyond the syscall (modprobe is a good one!) then exercise it
> > in a way so that there are no N-byte holes left in the arena, then
> > trigger an N-byte vmalloc().
>
> Well modprobe is root-only, so that's not so bad.
Even if it's root-only, we can still end up with a toasted machine.
Accidentally toasted, not deliberately.
> But it looks like
> key_add (see other thread from this evening) and probably others can be
> called as a user and gobble up vmalloc space. omnomnom.
hm, the keys code appears to prevent the user from reserving more than
20000 bytes of memory total (key_payload_reserve()), so it doesn't look
very useful for screwing up vmalloc().
next prev parent reply other threads:[~2012-03-29 2:24 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-03-13 18:22 suppress page allocation failure warnings from sys_listxattr Dave Jones
2012-03-13 21:33 ` Colin Walters
2012-03-27 22:51 ` Andrew Morton
2012-03-28 0:15 ` Dave Jones
2012-03-28 0:26 ` Andrew Morton
2012-03-28 7:13 ` David Rientjes
2012-03-28 4:39 ` Dave Chinner
2012-03-28 23:47 ` Andrew Morton
2012-03-29 0:54 ` Dave Jones
2012-03-29 1:10 ` Andrew Morton
2012-03-29 1:28 ` Joe Perches
2012-03-29 1:46 ` Andrew Morton
2012-03-29 1:50 ` Dave Jones
2012-03-29 2:02 ` Andrew Morton
2012-03-29 2:08 ` Dave Jones
2012-03-29 2:28 ` Andrew Morton [this message]
2012-03-29 3:00 ` Dave Jones
2012-03-29 21:09 ` Andrew Morton
2012-03-29 21:13 ` Dave Jones
2012-03-29 5:35 ` Dave Chinner
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