Re: [S390] cio: kernel stack overflow.

From: Heiko Carstens
Date: Wed Aug 30 2006 - 15:17:03 EST


On Wed, Aug 30, 2006 at 07:05:54PM +0000, David Wagner wrote:
> Thanks for pointing out that in most cases there was immediately
> preceding code that zeroes out the whole struct using kzalloc() or
> memset(.., 0, ..). Sorry that I overlooked that; my mistake. That
> takes care of all but one of these. But in the interests of caution,
> let me ask about the following one:
>
> Martin Schwidefsky wrote:
> >- cdev->id = (struct ccw_device_id) {
> >- .cu_type = cdev->private->senseid.cu_type,
> >- .cu_model = cdev->private->senseid.cu_model,
> >- .dev_type = cdev->private->senseid.dev_type,
> >- .dev_model = cdev->private->senseid.dev_model,
> >- };
> >+ cdev->id.cu_type = cdev->private->senseid.cu_type;
> >+ cdev->id.cu_model = cdev->private->senseid.cu_model;
> >+ cdev->id.dev_type = cdev->private->senseid.dev_type;
> >+ cdev->id.dev_model = cdev->private->senseid.dev_model;
>
> I don't see any obvious place that zeroes out cdev->id.
> In particular, it looks like cdev->id.match_flags and .driver_info
> are never cleared (i.e., they retain whatever old garbage they had
> before). More importantly, if anyone ever adds any more fields to
> struct ccw_device_id, then they will also be retain old garbage values,
> which is a maintenance pitfall. Is this right, or did I miss something
> again?

You're right. Thanks for pointing this out! I will take care of it.
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