linux-kernel - Re: BUG() on apm resume in 2.6.18-rc2

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: <20060727000856.f75d2603.akpm@osdl.org>
Date:	Thu, 27 Jul 2006 00:08:56 -0700
From:	Andrew Morton <akpm@...l.org>
To:	Johannes Weiner <hnazfoo@...glemail.com>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: BUG() on apm resume in 2.6.18-rc2

On Thu, 27 Jul 2006 08:29:32 +0200
Johannes Weiner <hnazfoo@...glemail.com> wrote:

> Hi,
> 
> On Wed, Jul 26, 2006 at 11:10:49PM -0700, Andrew Morton wrote:
> > This?
> > 
> > --- a/./arch/i386/kernel/cpu/mcheck/mce.h~mce-section-fix
> > +++ a/./arch/i386/kernel/cpu/mcheck/mce.h
> > @@ -9,6 +9,6 @@ void winchip_mcheck_init(struct cpuinfo_
> >  /* Call the installed machine check handler for this CPU setup. */
> >  extern fastcall void (*machine_check_vector)(struct pt_regs *, long error_code);
> >  
> > -extern int mce_disabled __initdata;
> > +extern int mce_disabled;
> >  extern int nr_mce_banks;
> 
> What hinted you to that? I didn't read much oopses, so...
> 

(please always do reply-to-all)

That was an easy one - it crashed at

EIP is at mcheck_init+0x4/0x80

right at the start of mcheck_init(), so it had to be the access of
mce_disabled.

It accessed the address c0729c38:

BUG: unable to handle kernel paging request at virtual address c0729c38

and the code dump shows an access to that address.

And the only way in which an access to a global variable of this nature can
oops is if that variable has been unmapped from the kenrel address space. 
We unmap (and reuse) the __init memory, so it had to be a sectioning bug.
-
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/