Re: [PATCH] rt2x00: reset reg earlier in rt2500usb_register_read

[慕冬亮]

On Thu, Jan 21, 2021 at 7:21 PM Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
>
> On Thu, Jan 21, 2021 at 06:59:08PM +0800, 慕冬亮 wrote:
> > > >       rt2x00usb_vendor_request_buff(rt2x00dev, USB_MULTI_READ,
> > > >                                     USB_VENDOR_REQUEST_IN, offset,
> > > >                                     &reg, sizeof(reg));
> > >
> > > Are you sure this is valid to call this function with a variable on the
> > > stack like this?  How did you test this change?
> >
> > First, I did not do any changes to this call. Second, the programming
> > style to pass the pointer of stack variable as arguments is not really
> > good. Third, I check this same code file, there are many code snippets
> > with such programming style. :(
>
> I know you did not change it, what I am asking is how did you test this
> change works?  I think the kernel will warn you in huge ways that using
> this pointer on the stack is incorrect, which implies you did not test
> this change :(
>

I tested this patch only with PoC. The patched kernel version did not
crash when executing the PoC.

BTW, I did not take notice of the warning information as there are
many many warnings in building KMSAN.

> thanks,
>
> greg k-h