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Message-ID: <CAMZ6RqJoCEW9+Z+LD1W9CORE=RUvH9tLn163mkY5Dsct5juYUA@mail.gmail.com>
Date: Sun, 11 Dec 2022 20:24:29 +0900
From: Vincent MAILHOL <mailhol.vincent@...adoo.fr>
To: Johan Hovold <johan@...nel.org>
Cc: Marc Kleine-Budde <mkl@...gutronix.de>, linux-can@...r.kernel.org,
Oliver Neukum <oneukum@...e.com>,
Wolfgang Grandegger <wg@...ndegger.com>,
"David S . Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>,
Frank Jungclaus <frank.jungclaus@....eu>, socketcan@....eu,
Yasushi SHOJI <yashi@...cecubics.com>,
Stefan Mätje <stefan.maetje@....eu>,
Hangyu Hua <hbh25y@...il.com>,
Oliver Hartkopp <socketcan@...tkopp.net>,
Peter Fink <pfink@...ist-es.de>,
Jeroen Hofstee <jhofstee@...tronenergy.com>,
Christoph Möhring <cmoehring@...ist-es.de>,
John Whittington <git@...engineering.co.uk>,
Vasanth Sadhasivan <vasanth.sadhasivan@...sara.com>,
Jimmy Assarsson <extja@...ser.com>,
Anssi Hannula <anssi.hannula@...wise.fi>,
Pavel Skripkin <paskripkin@...il.com>,
Stephane Grosjean <s.grosjean@...k-system.com>,
Wolfram Sang <wsa+renesas@...g-engineering.com>,
"Gustavo A . R . Silva" <gustavoars@...nel.org>,
Julia Lawall <Julia.Lawall@...ia.fr>,
Dongliang Mu <dzm91@...t.edu.cn>,
Sebastian Haas <haas@...-wuensche.com>,
Maximilian Schneider <max@...neidersoft.net>,
Daniel Berglund <db@...ser.com>,
Olivier Sobrie <olivier@...rie.be>,
Remigiusz Kołłątaj
<remigiusz.kollataj@...ica.com>,
Jakob Unterwurzacher <jakob.unterwurzacher@...obroma-systems.com>,
Martin Elshuber <martin.elshuber@...obroma-systems.com>,
Bernd Krumboeck <b.krumboeck@...il.com>,
netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
Alan Stern <stern@...land.harvard.edu>,
linux-usb@...r.kernel.org
Subject: Re: [PATCH v2 1/9] can: ems_usb: ems_usb_disconnect(): fix NULL
pointer dereference
On Tue. 10 déc. 2022 à 20:02, Johan Hovold <johan@...nel.org> wrote:
> On Sat, Dec 10, 2022 at 06:01:49PM +0900, Vincent Mailhol wrote:
> > ems_usb sets the driver's priv data to NULL before waiting for the
> > completion of outsdanding urbs. This can results in NULL pointer
> > dereference, c.f. [1] and [2].
>
> Please stop making hand-wavy claims like this. There is no risk for a
> NULL-pointer deference here, and if you think otherwise you need to
> explain how that can happen in detail for each driver.
Understood.
*My* mistake comes from this message from Alan [1]:
| But if a driver does make the call, it should be careful to
| ensure that the call happens _after_ the driver is finished
| using the interface-data pointer. For example, after all
| outstanding URBs have completed, if the completion handlers
| will need to call usb_get_intfdata().
I did not pay enough attention to the "if the completion handlers will
need to call usb_get_intfdata()" part and jumped into the incorrect
conclusion that any use of usb_set_intfdata(intf, NULL) before URB
completion was erroneous.
My deep apologies for all the noise. Please forget this series and one
more time, thank you for your patience.
[1] https://lore.kernel.org/linux-usb/Y4OD70GD4KnoRk0k@rowland.harvard.edu/
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