Re: usb_wwan regression in 3.6 kernel (bisected to bulk-urb allocation)

[Johan Hovold <jhovold-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

On Thu, Apr 03, 2014 at 08:49:40AM +0200, Rafał Miłecki wrote:
> I recently wanted to use my ZTE MF636 modem 19d2:0031 and got NULL
> pointer dereference in usb_wwan_write few seconds after plugging it.
> This is 100% reproducible.
> 
> BUG: unable to handle kernel NULL pointer dereference at 0000000000000058
> IP: [<ffffffffa07b9570>] usb_wwan_write+0xa0/0x2b0 [usb_wwan]
> 
> I've bisected between 3.4 and 3.14 kernels and it has appeared to be a
> regression caused by:
> 
> commit 8e493ca1767d4951ed1322abaa74d6edbca29918
> Author: Johan Hovold <jhovold-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> Date: Fri Oct 26 18:44:20 2012 +0200
> 
>     USB: usb_wwan: fix bulk-urb allocation
> 
>     Make sure we do not allocate urbs if we do not have a bulk endpoint.
> 
>     Legacy code used incorrect assumption to test for bulk endpoints.
> 
> Reverting above patch from the 3.14 release fixes the NULL pointer
> dereference for me.
> 
> Could you look into this, please? I can test any debug/fix patches you provide.

Thanks for the detailed report. Could you also provide the output of

	lsusb -vd 19d2:0031

Thanks,
Johan
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