netdev - Re: [Bugme-new] [Bug 33502] New: Caught 64-bit read from uninitialized memory in __alloc

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: <alpine.DEB.2.00.1105091502260.26839@router.home>
Date:	Mon, 9 May 2011 15:04:07 -0500 (CDT)
From:	Christoph Lameter <cl@...ux.com>
To:	Pekka Enberg <penberg@...nel.org>
cc:	Eric Dumazet <eric.dumazet@...il.com>,
	Pekka Enberg <penberg@...helsinki.fi>,
	casteyde.christian@...e.fr,
	Andrew Morton <akpm@...ux-foundation.org>,
	netdev@...r.kernel.org, bugzilla-daemon@...zilla.kernel.org,
	bugme-daemon@...zilla.kernel.org,
	Vegard Nossum <vegardno@....uio.no>
Subject: Re: [Bugme-new] [Bug 33502] New: Caught 64-bit read from uninitialized
 memory in __alloc_skb

On Mon, 9 May 2011, Pekka Enberg wrote:

> On Wed, 20 Apr 2011, Eric Dumazet wrote:
> > [PATCH v4] slub: dont use cmpxchg_double if KMEMCHECK or DEBUG_PAGEALLOC
> >
> > Christian Casteyde reported a KMEMCHECK splat in slub code.
> >
> > Problem is now we are lockless and allow IRQ in slab_alloc(), the object
> > we manipulate from freelist can be allocated and freed right before we
> > try to read object->next.
> >
> > Same problem can happen with DEBUG_PAGEALLOC
> >
> > Just dont use cmpxchg_double() if either CONFIG_KMEMCHECK or
> > CONFIG_DEBUG_PAGEALLOC is defined.
>
> Christoph, Eric, is this still relevant after commit 1759415 ("slub: Remove
> CONFIG_CMPXCHG_LOCAL ifdeffery") in slab/next of slab.git?

There is still an issue and now you can no longer fix the thing through
CONFIG_CMPXCHG_LOCAL.

It needs to be legal for slub to deref the counter even if the object has
been freed.

--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html