From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from aotearoadigitalarts.org.nz ([72.14.179.101]:57872 "EHLO linode.halo.gen.nz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750956Ab2GGD2I (ORCPT ); Fri, 6 Jul 2012 23:28:08 -0400 Message-ID: <4FF7ACBD.1040609@paradise.net.nz> Date: Sat, 07 Jul 2012 15:27:57 +1200 From: Douglas Bagnall MIME-Version: 1.0 To: Mauro Carvalho Chehab CC: linux-media@vger.kernel.org Subject: Re: [PATCH v2] Avoid sysfs oops when an rc_dev's raw device is absent References: <4FE7AA34.8090304@paradise.net.nz> <4FF64C60.1070804@redhat.com> In-Reply-To: <4FF64C60.1070804@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-media-owner@vger.kernel.org List-ID: For some reason, when the lirc daemon learns that a usb remote control has been unplugged, it wants to read the sysfs attributes of the disappearing device. This is useful for uncovering transient inconsistencies, but less so for keeping the system running when such inconsistencies exist. Under some circumstances (like every time I unplug my dvb stick from my laptop), lirc catches an rc_dev whose raw event handler has been removed (presumably by ir_raw_event_unregister), and proceeds to interrogate the raw protocols supported by the NULL pointer. This patch avoids the NULL dereference, and ignores the issue of how this state of affairs came about in the first place. Version 2 incorporates changes recommended by Mauro Carvalho Chehab (-ENODEV instead of -EINVAL, and a signed-off-by). Signed-off-by: Douglas Bagnall --- drivers/media/rc/rc-main.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/media/rc/rc-main.c b/drivers/media/rc/rc-main.c index 6e16b09..9880926 100644 --- a/drivers/media/rc/rc-main.c +++ b/drivers/media/rc/rc-main.c @@ -775,10 +775,12 @@ static ssize_t show_protocols(struct device *device, if (dev->driver_type == RC_DRIVER_SCANCODE) { enabled = dev->rc_map.rc_type; allowed = dev->allowed_protos; - } else { + } else if (dev->raw) { enabled = dev->raw->enabled_protocols; allowed = ir_raw_get_allowed_protocols(); } + else + return -ENODEV; IR_dprintk(1, "allowed - 0x%llx, enabled - 0x%llx\n", (long long)allowed,