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Date: Wed, 04 Jun 2014 12:13:01 -0400
From: Mike Remski <mremski@mutualink.net>
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To: Johan Hovold <jhovold@gmail.com>
CC: linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org
Subject: Re: ftdi_sio BUG: NULL pointer dereference
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On 06/04/2014 12:00 PM, Johan Hovold wrote:
> On Wed, Jun 04, 2014 at 11:41:47AM -0400, Mike Remski wrote:
>> Ok, had a chance to try the cdc-acm;  yes it's the ancient one that is
>> in the base install of CentOS 6.4 (2.6.32-71.29.1 centos patched).  I'm
>> hitting something similar;  I noticed there where a few commits for NULL
>> pointer dereferences in cdc-acm.c.
>>
>> I'll poke into this a bit (yes, I know try a newer kernel, etc) and let
>> you know what I find (or perhaps this looks similar to something already
>> seen?).  This device is the same as the original ftdi crash, 1.2 is the
>> same interface with bNumEndpoints == 0.
>>
>> Jun  4 11:35:20 nicA91A84 kernel: cdc_acm 5-2:1.2: This device cannot do
>> calls on its own. It is not a modem.
>> Jun  4 11:35:20 nicA91A84 kernel: BUG: unable to handle kernel NULL
>> pointer dereference at 00000004
>> Jun  4 11:35:20 nicA91A84 kernel: IP: [<f84f9c9e>]
>> acm_probe+0x44e/0x127c [cdc_acm]
>> Jun  4 11:35:20 nicA91A84 kernel: *pdpt = 00000000354eb001 *pde =
>> 000000007f003067
>> Jun  4 11:35:20 nicA91A84 kernel: Oops: 0000 [#1] SMP
>> Jun  4 11:35:20 nicA91A84 kernel: last sysfs file:
>> /sys/devices/pci0000:00/0000:00:1d.0/usb5/5-2/product
> Yeah, you really need to update your kernel. You'll definitely need at
> least commit 99f347caa456 ("USB: CDC ACM: Fix NULL pointer
> dereference").
>
> No more reports until you've tried a recent kernel, ok? ;)
>
> Johan
Agreed.  But I still have to understand it so I can backport the 
appropriate fixes, no?
I'll be quiet now.

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