Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965096AbaLKPbg (ORCPT ); Thu, 11 Dec 2014 10:31:36 -0500 Received: from mx1.redhat.com ([209.132.183.28]:53477 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933677AbaLKPbe (ORCPT ); Thu, 11 Dec 2014 10:31:34 -0500 Date: Thu, 11 Dec 2014 10:31:18 -0500 From: Benjamin Tissoires To: Peter Wu Cc: Jiri Kosina , Nestor Lopez Casado , Andrew de los Reyes , Peter Hutterer , linux-input@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 4/4] HID: logitech-hidpp: disable io in probe error path Message-ID: <20141211153118.GF29747@mail.corp.redhat.com> References: <1418302280-14794-1-git-send-email-peter@lekensteyn.nl> <1418302280-14794-5-git-send-email-peter@lekensteyn.nl> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <1418302280-14794-5-git-send-email-peter@lekensteyn.nl> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Dec 11 2014 or thereabouts, Peter Wu wrote: > Balance a hid_device_io_start() call with hid_device_io_stop() in the > error path. This avoids processing of HID reports when the probe fails > which possibly leads to invalid memory access in hid_device_probe() as > report_enum->report_id_hash might already be freed via > hid_close_report(). Well spotted too! > > hid_set_drvdata() is called before wtp_allocate, be consistent and clear > drvdata too on the error path of wtp_allocate. This is not strictly speaking required. We will have a dangling value in hdev->private_data, but this should be overwritten before the next use. Anyway, it makes sense to clean up after a failure, so the patch is Reviewed-by: Benjamin Tissoires Cheers, Benjamin > > Signed-off-by: Peter Wu > --- > Hi Andrew, > > There are few users of hid_device_io_start/stop, this is the first one > to get start/stop out of sync. Should the comment of > hid_device_io_start() be updated to ensure that hid_device_io_stop() > gets called before probe() returns? Or should the hid-core be changed to > handle this out-of-sync issue: > > if (ret) { > if (hdev->io_started)) > down(&hdev->driver_input_lock); > hid_close_report(hdev); > hdev->driver = NULL; > } > > Is my observation correct or not that HID reports can arrive during > hid_close_report() when io_started == true? > > Kind regards, > Peter > --- > drivers/hid/hid-logitech-hidpp.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/drivers/hid/hid-logitech-hidpp.c b/drivers/hid/hid-logitech-hidpp.c > index 4292cc3..2f420c0 100644 > --- a/drivers/hid/hid-logitech-hidpp.c > +++ b/drivers/hid/hid-logitech-hidpp.c > @@ -1121,7 +1121,7 @@ static int hidpp_probe(struct hid_device *hdev, const struct hid_device_id *id) > if (hidpp->quirks & HIDPP_QUIRK_CLASS_WTP) { > ret = wtp_allocate(hdev, id); > if (ret) > - return ret; > + goto wtp_allocate_fail; > } > > INIT_WORK(&hidpp->work, delayed_work_cb); > @@ -1141,6 +1141,7 @@ static int hidpp_probe(struct hid_device *hdev, const struct hid_device_id *id) > if (id->group != HID_GROUP_LOGITECH_DJ_DEVICE) { > if (!connected) { > hid_err(hdev, "Device not connected"); > + hid_device_io_stop(hdev); > goto hid_parse_fail; > } > > @@ -1186,6 +1187,7 @@ hid_hw_start_fail: > hid_parse_fail: > cancel_work_sync(&hidpp->work); > mutex_destroy(&hidpp->send_mutex); > +wtp_allocate_fail: > hid_set_drvdata(hdev, NULL); > return ret; > } > -- > 2.1.3 > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/