Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754925Ab0BUJL3 (ORCPT ); Sun, 21 Feb 2010 04:11:29 -0500 Received: from mail.windriver.com ([147.11.1.11]:40436 "EHLO mail.windriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754173Ab0BUJL1 (ORCPT ); Sun, 21 Feb 2010 04:11:27 -0500 Message-ID: <4B80FA08.8080304@windriver.com> Date: Sun, 21 Feb 2010 17:16:56 +0800 From: DDD User-Agent: Thunderbird 2.0.0.22 (X11/20090608) MIME-Version: 1.0 To: =?UTF-8?B?QW3DqXJpY28gV2FuZw==?= CC: rusty@rustcorp.com.au, davem@davemloft.net, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, jason.wessel@windriver.com, lenb@kernel.org, dwmw2@infradead.org, mdharm-usb@one-eyed-alien.net, bfields@fieldses.org, robert.richter@amd.com Subject: Re: [PATCH] module param_call: fix potential NULL pointer dereference References: <1266737078-26186-1-git-send-email-dongdong.deng@windriver.com> <2375c9f91002210041l1bf30871vdf3881589a654d5a@mail.gmail.com> In-Reply-To: <2375c9f91002210041l1bf30871vdf3881589a654d5a@mail.gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-OriginalArrivalTime: 21 Feb 2010 09:10:53.0793 (UTC) FILETIME=[C517CD10:01CAB2D5] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1947 Lines: 65 Américo Wang wrote: > On Sun, Feb 21, 2010 at 3:24 PM, Dongdong Deng > wrote: >> The param_set_fn() function will get a parameter which is a NULL >> pointer when insmod module with params via following method: >> >> $insmod module.ko module_params >> >> BTW: the normal method usually as following format: >> $insmod module.ko module_params=example >> >> If the param_set_fn() function didn't check that parameter and used >> it directly, it could caused an OOPS due to NULL pointer dereference. >> >> The solution is simple: >> Just checking the parameter before using in param_set_fn(). >> >> Example: >> int set_module_params(const char *val, struct kernel_param *kp) >> { >> /*Checking the val parameter before using */ >> if (!val) >> return -EINVAL; >> ... >> } >> module_param_call(module_params, set_module_params, NULL, NULL, 0644); >> > > Why not just checking all of them in the generic code? It is no problem that we check the params before invoking param_set_fn(). But I trend to do the checking in param_set_*fn(), because we can offer some special prompt infos to user if we want and handle some special cases like param_set_bool(). Thanks, Dongdong > How about my _untested_ patch below? > > Thanks. > > ----------- > > When a module parameter "foo" is not bool, we shouldn't accept arguments > like this "insmod ./foo.ko foo". However, currently only standard > ->set functions > check this, several non-standard ->set functions ignore this, thus could cause > NULL def oops. > > Reported-by: Dongdong Deng > Signed-off-by: WANG Cong > > --- > -- 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/