Re: PCI/e1000 BUG: unable to handle kernel paging request at 0ffff163

From: Fengguang Wu
Date: Thu Sep 06 2012 - 05:05:19 EST


On Wed, Sep 05, 2012 at 11:41:04AM -0700, Yinghai Lu wrote:
> On Tue, Sep 4, 2012 at 11:51 PM, Fengguang Wu <fengguang.wu@xxxxxxxxx> wrote:
> > Yinghai,
> >
> > There are many kernel paging errors showing up in tree:
> >
> > git://git.kernel.org/pub/scm/linux/kernel/git/yinghai/linux-yinghai.git for-pci-for-each-res-addon-v2
> >
> > The below summary shows that
> >
> > 1) it's a reliably reproducible bug
> > 2) all paging fault happens at address 0ffff163 and in some e1000 functions
> >
> > I'll try to bisect if the root cause is not obvious to you. (Cannot
> > do so for now because there are 3 bisections on the way and I cannot
> > afford more..)
>
> thanks, will check that...

Yinghai, I'm very sorry that it's a false report...

The root cause is memory corruption by the isdnloop driver:

==> [ 9.345694] isdnloop-ISDN-driver Rev 1.11.6.7
==> [ 9.347484] isdnloop: (loop0) virtual card added
[ 9.348444] bus: 'usb': driver_probe_device: matched device 1-1:2.0 with driver cdc_acm
[ 9.349773] bus: 'usb': really_probe: probing driver cdc_acm with device 1-1:2.0
[ 9.350967] cdc_acm 1-1:2.0: This device cannot do calls on its own. It is not a modem.
[ 9.353255] cdc_acm 1-1:2.0: ttyACM0: USB ACM device
[ 9.354137] BUG: unable to handle kernel paging request at 0ffff163
[ 9.355214] IP: [<0ffff163>] 0xffff162
[ 9.355869] *pde = 00000000

Which was recently fixed by

commit 77f00f6324cb97cf1df6f9c4aaeea6ada23abdb2
Author: Wu Fengguang <fengguang.wu@xxxxxxxxx>
Commit: David S. Miller <davem@xxxxxxxxxxxxx>
CommitDate: Fri Aug 3 16:53:22 2012 -0700

isdnloop: fix and simplify isdnloop_init()

Fix a buffer overflow bug by removing the revision and printk.

Thanks,
Fengguang
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