From mboxrd@z Thu Jan 1 00:00:00 1970 From: Richard Leitner Subject: [RFC] avoid (theoretical) conflicts of input device file names Date: Wed, 8 Oct 2014 22:49:29 +0200 Message-ID: <20141008224929.290e6403@frodo> References: <20141008224245.601a1339@frodo> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: Received: from relay05.alfahosting-server.de ([109.237.142.241]:53412 "EHLO relay05.alfahosting-server.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752172AbaJHUtf (ORCPT ); Wed, 8 Oct 2014 16:49:35 -0400 In-Reply-To: <20141008224245.601a1339@frodo> Sender: linux-input-owner@vger.kernel.org List-Id: linux-input@vger.kernel.org To: dmitry.torokhov@gmail.com Cc: linux-input@vger.kernel.org, linux-kernel@vger.kernel.org, richard.leitner@skidata.com Hi, currently I discovered the possibility that device file numbers of the input subsystem could go negative when the signed int "border" is passed. To fix this behaviour I sent a patch a few minutes ago. But as the subject says there is currently the (theoretical) possibility that the same input device file name is given out twice. This can happen if the "input_no" variable had an overflow (due to the fact this is at least at 2^32 I call the issue theoretical). If such a case occurs a -EEXISTS is returned at the creation of the file. IMHO it would be a good idea to check if the chosen input device file name is valid at the point it is created (which is currently input_allocate_device). So you can just increment and check it again until there's a valid number/name found for it. I'm pretty new to the input subsystem, so what do you think about it? Any comments/ideas? Would there be a better place to do such checking? regards, richard