Date: Thu, 05 May 2005 16:00:55 -0600 (MDT) From: Warner Losh <imp@bsdimp.com> To: julian@elischer.org Cc: usbcrash@oldach.net Subject: Re: recent USB MFCs cause panics Message-ID: <20050505.160055.78800132.imp@bsdimp.com> In-Reply-To: <427A9690.9080108@elischer.org> References: <427A8EF3.70003@elischer.org> <20050505.153302.71182158.imp@bsdimp.com> <427A9690.9080108@elischer.org>
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From: Julian Elischer <julian@elischer.org>
Subject: Re: recent USB MFCs cause panics
Date: Thu, 05 May 2005 14:56:32 -0700
>
>
> Warner Losh wrote:
>
> >From: Julian Elischer <julian@elischer.org>
> >Subject: Re: recent USB MFCs cause panics
> >Date: Thu, 05 May 2005 14:24:03 -0700
> >
> >
> >
> >>Julian Elischer wrote:
> >>
> >>try:
> >>
> >>in usb_port.h
> >>comment out line 425 (as below)
> >>
> >>422
> >> 423 #define config_detach(dev, flag) \
> >> 424 do { \
> >> 425 /* device_detach(dev); */ \
> >> 426 free(device_get_ivars(dev), M_USB); \
> >> 427 device_delete_child(device_get_parent(dev), dev); \
> >> 428 } while (0);
> >> 429
> >>
> >>
> >
> >Commenting it out is lame... I fixed this in current in uhub.c as
> >well as here... Since 'dev' is 0 here, I'm unsure that commenting it
> >out will fix the problem because the next line frees it....
> >
> >
>
> yes I noticed that..
> the next line doesn't free it, it frees the ivars
> which I don't think is the same thing..
if dev is NULL, then freeing the ivars from dev will still result in a
NULL pointer dereference...
> the problem is that the 5.0 code does the device_delete_child() (as you
> see above)
> where 4.x did it in the device_detach()
> so with this merge I get the worst of both worlds..
>
> the answer is to make uhub.c not call it's bus_child_detached() method
> (as 5.0 doesn't)
> or to make it a null function, as it clears the subdev entry which
> causes this problem.
Yes. I think that's the more correct fix.
Warner
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