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From: Greg KH <gregkh@linuxfoundation.org>
To: "Schmid, Carsten" <Carsten_Schmid@mentor.com>
Cc: Hans de Goede <hdegoede@redhat.com>,
	Alan Stern <stern@rowland.harvard.edu>,
	Andrey Konovalov <andreyknvl@google.com>,
	Oliver Neukum <oneukum@suse.com>,
	syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
	syzbot <syzbot+ef5de9c4f99c4edb4e49@syzkaller.appspotmail.com>,
	USB list <linux-usb@vger.kernel.org>,
	Hillf Danton <hdanton@sina.com>
Subject: Re: AW: AW: KASAN: use-after-free Read in usbhid_power
Date: Fri, 9 Aug 2019 14:54:58 +0200
Message-ID: <20190809125458.GA2230@kroah.com> (raw)
In-Reply-To: <932dbc769a80416eb736e6397c126ce9@SVR-IES-MBX-03.mgc.mentorg.com>

On Fri, Aug 09, 2019 at 12:38:35PM +0000, Schmid, Carsten wrote:
> Hi again,
> 
> >>
> >> Hey, i did not want to trigger an eartquake in the basement of the kernel ;-)
> >> My intention was to prevent some crashes, and help developers to find their bugs.
> >> I think my patch exactly does this.
> > 
> > Hehe, actually drivers not being able to block unbind has been bugging me
> > for
> > a while now, because there are cases where this would be really helpful.
> >>> 1) make resources refcounted, have child resources take a ref on the parent
> >>> 2) Disallow unbind on devices with bound child-devices?
> >>>
> >> Exactly what i was thinking of in first attempts.
> >> But i fear that would break even more use cases.
> >>
> >> Hans, directly regarding the driver:
> >> The problem i see is that the xhci_intel_unregister_pdev which is added
> >> as an action with devm_add_action_or_reset() is called late by the framework,
> >> later than the usb_hcd_pci_remove() in xhci_pci_remove.
> >> Is there any chance to trigger this before?
> >> This is what Greg meant with "right order".
> > 
> > Ah, I missed that part, sure that should be easy, just stop using
> > devm_add_action_or_reset() and do the xhci_intel_unregister_pdev()
> > manually at the right time. The downside of this is that you also
> > need to make sure it happens at the right time from probe error-paths
> > but given the bug you are hitting, I guess that is probably
> > already a problem.
> > 
> @Hans:
> Sure, will have a look at this. I think i have found where to do that,
> but need to check how to get the pdev pointer there ....
> 
> @Greg:
> I am still confident that my patch in __release_region should be taken in.

Ok, submit it in a "real" way and we can consider it :)

thanks,

greg k-h

  reply index

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-23 12:48 syzbot
2019-07-24 14:17 ` Oliver Neukum
2019-07-24 14:24   ` Andrey Konovalov
2019-07-24 20:55 ` Oliver Neukum
2019-07-24 21:02   ` Alan Stern
2019-07-25  9:33     ` Oliver Neukum
2019-07-25 15:09       ` Alan Stern
2019-08-08 18:54         ` Andrey Konovalov
2019-08-08 19:37           ` Alan Stern
2019-08-09  7:35             ` AW: " Schmid, Carsten
2019-08-09  7:55               ` Greg KH
2019-08-09  9:34                 ` AW: " Schmid, Carsten
2019-08-09 10:20                   ` Hans de Goede
2019-08-09 10:47                     ` AW: " Schmid, Carsten
2019-08-09 10:53                       ` Hans de Goede
2019-08-09 12:38                         ` AW: " Schmid, Carsten
2019-08-09 12:54                           ` Greg KH [this message]
2019-08-09 13:00                             ` Schmid, Carsten
2019-08-09 13:38                               ` Greg KH
2019-08-10 11:12                           ` AW: " Hans de Goede
2019-08-09 17:36             ` Andrey Konovalov
2019-08-09 18:12               ` syzbot
2019-08-12 14:29                 ` Andrey Konovalov
2019-08-09 20:26           ` Oliver Neukum
2019-07-24 21:16   ` syzbot
2019-07-25 11:22     ` Andrey Konovalov
2019-07-25 12:15 ` Oliver Neukum
2019-07-25 12:27   ` syzbot

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