linux-kernel - Re: [sched-devel/latest] WARNING: at mm/slub.c:2443

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:	Wed, 23 Apr 2008 20:35:15 +0300
From:	"Pekka Enberg" <penberg@...helsinki.fi>
To:	"Pete Zaitcev" <zaitcev@...hat.com>
Cc:	"Ingo Molnar" <mingo@...e.hu>, "Frans Pop" <elendil@...net.nl>,
	linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org,
	gregkh@...e.de, "Christoph Lameter" <clameter@....com>
Subject: Re: [sched-devel/latest] WARNING: at mm/slub.c:2443

On Wed, Apr 23, 2008 at 8:11 PM, Pete Zaitcev <zaitcev@...hat.com> wrote:
>  > --- a/drivers/usb/mon/mon_text.c
>  > +++ b/drivers/usb/mon/mon_text.c
>  > @@ -449,6 +449,7 @@ static struct mon_event_text *mon_text_read_wait(struct mon_reader_text *rp,
>  >               if (file->f_flags & O_NONBLOCK) {
>  >                       set_current_state(TASK_RUNNING);
>  >                       remove_wait_queue(&rp->wait, &waita);
>  > +                     kmem_cache_free(rp->e_slab, ep);
>  >                       return ERR_PTR(-EWOULDBLOCK);
>
>  The code looks like this:
>
>         while ((ep = mon_text_fetch(rp, mbus)) == NULL) {
>
>                 if (file->f_flags & O_NONBLOCK) {
>                         set_current_state(TASK_RUNNING);
>                         remove_wait_queue(&rp->wait, &waita);
>                         return ERR_PTR(-EWOULDBLOCK);
>
>  It's impossible to get inside the while() with non-null ep,
>  so your patch doesn't fix anything (even if kmem_cache_free
>  can survive a NULL object).

Yeah, I need a new pair of glasses. Thanks.

On Wed, Apr 23, 2008 at 8:11 PM, Pete Zaitcev <zaitcev@...hat.com> wrote:
>  Any other ideas?

Well, a race in mon_text_release() after the kmem_cache_free() loop
and the call to kmem_cache_destroy() but looks like that can't happen
either. Frans, is this easily triggerable? If so, can you try with
CONFIG_SLAB and CONFIG_DEBUG_SLAB enabled instead?
--
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/