From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dmitry Torokhov Subject: Re: [PATCH v2] HID: wacom: Prevent potential null dereference after disconnect Date: Wed, 8 Oct 2014 14:40:45 -0700 Message-ID: <20141008214045.GF15198@dtor-ws> References: <1412704473-6708-1-git-send-email-killertofu@gmail.com> <1412792742-4075-1-git-send-email-killertofu@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail-pa0-f54.google.com ([209.85.220.54]:49125 "EHLO mail-pa0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753607AbaJHVkt (ORCPT ); Wed, 8 Oct 2014 17:40:49 -0400 Content-Disposition: inline In-Reply-To: <1412792742-4075-1-git-send-email-killertofu@gmail.com> Sender: linux-input-owner@vger.kernel.org List-Id: linux-input@vger.kernel.org To: Jason Gerecke Cc: jkosina@suse.cz, benjamin.tissoires@gmail.com, pinglinux@gmail.com, linux-input@vger.kernel.org, linux-kernel@vger.kernel.org On Wed, Oct 08, 2014 at 11:25:42AM -0700, Jason Gerecke wrote: > Repeated connect/disconnect cycles under GNOME can trigger an occasional > OOPS from within e.g. wacom_led_select_store, presumably due to a timing > issue where userspace begins setting a value immediately before the > device disconnects and our shared data is whisked away. > > Signed-off-by: Jason Gerecke > --- > Changes in v2: > * Added in missing escape character > > drivers/hid/wacom_sys.c | 13 ++++++++++++- > 1 file changed, 12 insertions(+), 1 deletion(-) > > diff --git a/drivers/hid/wacom_sys.c b/drivers/hid/wacom_sys.c > index 8593047..265429b 100644 > --- a/drivers/hid/wacom_sys.c > +++ b/drivers/hid/wacom_sys.c > @@ -641,6 +641,9 @@ static ssize_t wacom_led_select_store(struct device *dev, int set_id, > unsigned int id; > int err; > > + if (!wacom) > + return -ENODEV; > + Strong NAK. If device could disappear before this check it could as well disappear after your check. This patch does not solve anything. > err = kstrtouint(buf, 10, &id); > if (err) > return err; Thanks. -- Dmitry