Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758762Ab0BYBsZ (ORCPT ); Wed, 24 Feb 2010 20:48:25 -0500 Received: from mail-qy0-f179.google.com ([209.85.221.179]:41439 "EHLO mail-qy0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753199Ab0BYBsY convert rfc822-to-8bit (ORCPT ); Wed, 24 Feb 2010 20:48:24 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=O65X5WioibdbP/i25pQ7cGqOvMPCKfETgccZiuGl/Abt/k2X7LgxU0F8yveySukG8e M0AWO3AdZxqM+H6LfeEF2024a907azmLpurRTJwAN3K3qF7Uk1mSlSXKr0j7fe42c8Tt 2l0illKJCAQH/ZGJves2gC8UL51r+enEtSJA4= MIME-Version: 1.0 In-Reply-To: <201002241131.16766.rusty@rustcorp.com.au> References: <1266835251-15457-1-git-send-email-dongdong.deng@windriver.com> <201002231426.45886.rusty@rustcorp.com.au> <20100223154519.GA4779@hack> <201002241131.16766.rusty@rustcorp.com.au> Date: Thu, 25 Feb 2010 09:48:22 +0800 Message-ID: <2375c9f91002241748h151b9592y246ccb0bcdb3a7b5@mail.gmail.com> Subject: Re: [RESEND PATCH] module param_call: fix potential NULL pointer dereference From: =?UTF-8?Q?Am=C3=A9rico_Wang?= To: Rusty Russell Cc: Dongdong Deng , linux-kernel@vger.kernel.org, Andrew Morton Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2926 Lines: 68 On Wed, Feb 24, 2010 at 9:01 AM, Rusty Russell wrote: > On Wed, 24 Feb 2010 02:15:19 am Américo Wang wrote: >> On Tue, Feb 23, 2010 at 02:26:45PM +1030, Rusty Russell wrote: >> >On Mon, 22 Feb 2010 09:10:51 pm Dongdong Deng wrote: >> >> The param_set_fn() function will get a parameter which is a NULL >> >> pointer when insmod module via bare params as following method: >> >> >> >> $insmod foo.ko foo >> >> >> >> 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: >> >> Using "" to replace NULL parameter, thereby the param_set_fn() >> >> function will never get a NULL pointer. >> > >> >This changes the value of booleans, and loses checking for int params, etc. >> > >> >I liked Americo's approach; I've combined the two approaches below. >> > >> >Since I'm going away, can Andrew take this? >> > >> >Subject: params: don't hand NULL values to param.set callbacks. >> > >> >An audit by Dongdong Deng revealed that most driver-author-written param >> >calls don't handle val == NULL (which happens when parameters are specified >> >with no =, eg "foo" instead of "foo=1"). >> > >> >The only real case to use this is boolean, so handle it specially for that >> >case and remove a source of bugs for everyone else as suggested by Americo. >> > >> >Signed-off-by: Rusty Russell >> >Cc: Dongdong Deng >> >Cc: Américo Wang >> > >> >diff --git a/kernel/params.c b/kernel/params.c >> >--- a/kernel/params.c >> >+++ b/kernel/params.c >> >@@ -59,6 +59,9 @@ static int parse_one(char *param, >> >     /* Find parameter */ >> >     for (i = 0; i < num_params; i++) { >> >             if (parameq(param, params[i].name)) { >> >+                    /* Noone handled NULL, so do it here. */ >> >+                    if (!val && params[i].set != param_set_bool) >> >+                            return -EINVAL; >> >> Sorry, after rethinking about this, I think it might be wrong. >> >> With this patch, when I use non-standard bool functions, I will not >> have a chance to use '!val' which should be valid for all bool >> functions. Or am I missing something? > > Sure, at that point we'd need something more sophisticated.  But to > fix this properly we want a flags word, and thus something like this > which I worked on earlier: > > http://ozlabs.org/~rusty/kernel/rr-latest/param:param_ops.patch > Thanks, Rusty! I love that patch, but since 2.6.33 is already out, can we try to get it merged for 2.6.34? -- 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/