From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751901AbaKJTW1 (ORCPT ); Mon, 10 Nov 2014 14:22:27 -0500 Received: from shards.monkeyblade.net ([149.20.54.216]:47042 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751399AbaKJTW0 (ORCPT ); Mon, 10 Nov 2014 14:22:26 -0500 Date: Mon, 10 Nov 2014 14:22:23 -0500 (EST) Message-Id: <20141110.142223.816257623301941276.davem@davemloft.net> To: sudipm.mukherjee@gmail.com Cc: steve.glendinning@shawell.net, netdev@vger.kernel.org, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] usbnet: smsc95xx: dereferencing NULL pointer From: David Miller In-Reply-To: <1415366560-27614-1-git-send-email-sudipm.mukherjee@gmail.com> References: <1415366560-27614-1-git-send-email-sudipm.mukherjee@gmail.com> X-Mailer: Mew version 6.6 on Emacs 24.3 / Mule 6.0 (HANACHIRUSATO) Mime-Version: 1.0 Content-Type: Text/Plain; charset=iso-8859-7 X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.5.7 (shards.monkeyblade.net [149.20.54.216]); Mon, 10 Nov 2014 11:22:26 -0800 (PST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from base64 to 8bit by nfs id sAAJMYJs031315 From: Sudip Mukherjee Date: Fri, 7 Nov 2014 18:52:40 +0530 > we were dereferencing dev to initialize pdata. but just after that we > have a BUG_ON(!dev). so we were basically dereferencing the pointer > first and then tesing it for NULL. > > Signed-off-by: Sudip Mukherjee You didn't even compile test this. Do not even bother fixing theoretical issues if you're going to be introducing a _REAL_ serious regression into the code with your "fix": drivers/net/usb/smsc95xx.c: In function smsc95xx_resume: drivers/net/usb/smsc95xx.c:1674:5: warning: pdata is used uninitialized in this function [-Wuninitialized] u8 suspend_flags = pdata->suspend_flags; ^ So, instead of a theoretical issue, we now have a real guaranteed crash. You did not compile test this change, and you definitely did not functionally test this change either. Please do not do this ever again, thanks. {.n++%ݶw{.n+{G{ayʇڙ,jfhz_(階ݢj"mG?&~iOzv^m ?I