From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752870AbdF0LAt (ORCPT ); Tue, 27 Jun 2017 07:00:49 -0400 Received: from frisell.zx2c4.com ([192.95.5.64]:49025 "EHLO frisell.zx2c4.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752821AbdF0LAY (ORCPT ); Tue, 27 Jun 2017 07:00:24 -0400 Date: Tue, 27 Jun 2017 13:00:16 +0200 From: "Jason A. Donenfeld" To: Greg Kroah-Hartman Cc: Kees Cook , Ingo Molnar , Peter Zijlstra , Thomas Hellstrom , Andi Kleen , Daniel Micay , linux-kernel@vger.kernel.org Subject: Re: [PATCH] kref: Avoid null pointer dereference after WARN Message-ID: <20170627110013.GA3026@zx2c4.com> References: <20170627035215.GA132342@beast> <20170627070626.GH29909@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20170627070626.GH29909@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 27, 2017 at 09:06:26AM +0200, Greg Kroah-Hartman wrote: > I remember one complaint was that WARN_ON was "huge" and this bloated > the kernel code a lot. But then that got fixed up. Is BUG_ON going to > cause the same complaint again? Complaint or not, I'm pretty sure using BUG_ON here is the right behavior. If removing it will result in a null pointer dereference (and subsequent function call), that's bad news bears, especially on systems with a zero mmap_min_addr or combined with other bugs. If somehow a driver manages to pass a NULL as the release function, something is really messed up and the kernel should "safely" panic instead. > > thanks, > > greg k-h -- Jason A. Donenfeld Deep Space Explorer fr: +33 6 51 90 82 66 us: +1 513 476 1200 www.jasondonenfeld.com www.zx2c4.com zx2c4.com/keys/AB9942E6D4A4CFC3412620A749FC7012A5DE03AE.asc