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SubjectRe: [PATCH] usb: gadget/composite : Avoid crash with bad gadget drivers
On Fri, Aug 09, 2013 at 09:23:08PM +0300, Philippe De Swert wrote:
> Some bad gadget drivers do not check the return status of usb_add_config.

fix the gadget driver

> Thus they get a not correctly initialized config and when this gadget gets
> deactivated the whole kernel crashes. Since on initialization failure cdev
> is set to NULL it can be used to detect this problem situation. It can be
> argued that the faulty gadget driver should be fixed, but imho it is better
> to avoid crashing the kernel and letting the gadget developer know he/she
> is making a mistake. And have the developer of said gadget driver then fix
> the problem of course.
>
> Signed-off-by: Philippe De Swert <philippe.deswert@jollamobile.com>
> ---
> drivers/usb/gadget/composite.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/drivers/usb/gadget/composite.c b/drivers/usb/gadget/composite.c
> index 55f4df6..e019bb5 100644
> --- a/drivers/usb/gadget/composite.c
> +++ b/drivers/usb/gadget/composite.c
> @@ -848,12 +848,18 @@ void usb_remove_config(struct usb_composite_dev *cdev,
> {
> unsigned long flags;
>
> + if (config->cdev == NULL) {
> + pr_warn("Calling usb_remove_config without a matching usb_add_config!\n");
> + goto end;
> + }

I would take a WARN() only, but let the crash happen and fix the gadget
driver.

--
balbi
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