Re: [PATCH v2] usb/core: usb_alloc_dev(): fix setting of ->portnum

[Alan Stern]

On Thu, 17 Mar 2016, Nicolai Stange wrote:

> With commit 69bec7259853 ("USB: core: let USB device know device node"),
> the port1 argument of usb_alloc_dev() gets overwritten as follows:
> 
>   ... usb_alloc_dev(..., unsigned port1)
>   {
>     ...
>     if (!parent->parent) {
>       port1 = usb_hcd_find_raw_port_number(..., port1);
>     }
>     ...
>   }
> 
> Later on, this now overwritten port1 gets assigned to ->portnum:
> 
>   dev->portnum = port1;
> 
> However, since xhci_find_raw_port_number() isn't idempotent, the
> aforementioned commit causes a number of KASAN splats like the following:

...

> Fix this by not overwriting the port1 argument in usb_alloc_dev(), but
> storing the raw port number as required by OF in an additional variable,
> raw_port.
> 
> Fixes: 69bec7259853 ("USB: core: let USB device know device node")
> Signed-off-by: Nicolai Stange <nicstange@xxxxxxxxx>
> ---
>  Applicable to linux-next-20160317
> 
>  Changes to v1:
>  - Initialize raw_port with port1

Acked-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>