linux-kernel - [PATCH 6/8] can: ucan: ucan_disconnect(): fix NULL pointer dereference

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Message-Id: <20221203133159.94414-7-mailhol.vincent@wanadoo.fr>
Date:   Sat,  3 Dec 2022 22:31:57 +0900
From:   Vincent Mailhol <mailhol.vincent@...adoo.fr>
To:     Marc Kleine-Budde <mkl@...gutronix.de>, linux-can@...r.kernel.org
Cc:     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>,
        Philipp Tomsich <philipp.tomsich@...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,
        Vincent Mailhol <mailhol.vincent@...adoo.fr>
Subject: [PATCH 6/8] can: ucan: ucan_disconnect(): fix NULL pointer dereference

ucan sets the usb_interface to NULL before waiting for the completion
of outstanding urbs. This can result in NULL pointer dereference,
c.f. [1] and [2].

Remove the call to usb_set_intfdata(intf, NULL). The core will take
care of setting it to NULL after ucan_disconnect() at [3].

[1] commit 27ef17849779 ("usb: add usb_set_intfdata() documentation")
Link: https://git.kernel.org/gregkh/usb/c/27ef17849779

[2] thread about usb_set_intfdata() on linux-usb mailing.
Link: https://lore.kernel.org/linux-usb/Y4OD70GD4KnoRk0k@rowland.harvard.edu/

[3] function usb_unbind_interface() from drivers/usb/core/driver.c
Link: https://elixir.bootlin.com/linux/v6.0/source/drivers/usb/core/driver.c#L497

Fixes: 9f2d3eae88d2 ("can: ucan: add driver for Theobroma Systems UCAN devices")
Signed-off-by: Vincent Mailhol <mailhol.vincent@...adoo.fr>
---
 drivers/net/can/usb/ucan.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/net/can/usb/ucan.c b/drivers/net/can/usb/ucan.c
index ffa38f533c35..429b3519ee7f 100644
--- a/drivers/net/can/usb/ucan.c
+++ b/drivers/net/can/usb/ucan.c
@@ -1579,8 +1579,6 @@ static void ucan_disconnect(struct usb_interface *intf)
 {
 	struct ucan_priv *up = usb_get_intfdata(intf);
 
-	usb_set_intfdata(intf, NULL);
-
 	if (up) {
 		unregister_candev(up->netdev);
 		free_candev(up->netdev);
-- 
2.37.4