From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B9C08CA9EC0 for ; Mon, 28 Oct 2019 14:42:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9355321744 for ; Mon, 28 Oct 2019 14:42:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390262AbfJ1Omr (ORCPT ); Mon, 28 Oct 2019 10:42:47 -0400 Received: from mx2.suse.de ([195.135.220.15]:57792 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727982AbfJ1Omr (ORCPT ); Mon, 28 Oct 2019 10:42:47 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 4F486B521; Mon, 28 Oct 2019 14:42:45 +0000 (UTC) Date: Mon, 28 Oct 2019 15:42:44 +0100 Message-ID: From: Takashi Iwai To: Dan Carpenter Cc: syzbot , alsa-devel@alsa-project.org, andreyknvl@google.com, benquike@gmail.com, g@b4.vu, linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org, perex@perex.cz, rfontana@redhat.com, syzkaller-bugs@googlegroups.com, tiwai@suse.com, yuehaibing@huawei.com Subject: Re: KASAN: slab-out-of-bounds Read in build_audio_procunit In-Reply-To: <20191028143406.GE1922@kadam> References: <000000000000df5189059580f8e9@google.com> <20191028143406.GE1922@kadam> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI/1.14.6 (Maruoka) FLIM/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL/10.8 Emacs/25.3 (x86_64-suse-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka") Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 28 Oct 2019 15:34:06 +0100, Dan Carpenter wrote: > > I wish that this could have been detected with static analysis... > > On Tue, Oct 22, 2019 at 05:45:14PM +0200, Takashi Iwai wrote: > > diff --git a/sound/usb/validate.c b/sound/usb/validate.c > > index 3c8f73a0eb12..a5e584b60dcd 100644 > > --- a/sound/usb/validate.c > > +++ b/sound/usb/validate.c > > @@ -75,7 +75,7 @@ static bool validate_processing_unit(const void *p, > > > > if (d->bLength < sizeof(*d)) > ^^^^^^^^^^^^^^^^^^^^^^^ > So we know that d->bLength is >= 10. > > > return false; > > - len = d->bLength < sizeof(*d) + d->bNrInPins; > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ > Len is 1 or 0. > > > + len = sizeof(*d) + d->bNrInPins; > > if (d->bLength < len) > ^^^^^^^^^^^^^^^^ > > So this condition can't be false. > > > return false; > > But it just makes this return into dead code and we have a lot of dead > code paths in the kernel so it doesn't make sense to generate a warning. > ... I don't know if I have a solution. > > Maybe some day we will have a vim pluggin which will highlight all the > dead paths and someone would notice that it that way. That'd be awesome :) Of even a simple checker code that can run in the git commit hook should suffice for careless maintainers like me. thanks, Takashi