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 Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id A0058C87FC9 for ; Tue, 29 Jul 2025 06:24:29 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ugdkw-0005f1-1t; Tue, 29 Jul 2025 02:24:10 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1ugdkk-0005aN-GW for qemu-trivial@nongnu.org; Tue, 29 Jul 2025 02:24:00 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1ugdki-0006w6-G4 for qemu-trivial@nongnu.org; Tue, 29 Jul 2025 02:23:58 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1753770233; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=XrMIcyi/rSA7+Fqudv9DCZ7+wbjqoc6Ybm/3cPcVf5A=; b=YYFyvhdyPUlAW6jaaYRfqxXmnXQGOVDP3JLybVOZiYLYNP2R7PfWptmAydFLWEg1D8j+4/ 0dJNbR8e8m1BLifZa2pFtMYanLRTtjcDFNxq4mSXo7KpiOfHbGcDywpPpletM/foq59dTY 9uUNf6gedjEMfuGzSbSnfQJcXXVGGAc= Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-312-oDJoKVkxMy2Qwp-Zw-AImw-1; Tue, 29 Jul 2025 02:23:52 -0400 X-MC-Unique: oDJoKVkxMy2Qwp-Zw-AImw-1 X-Mimecast-MFC-AGG-ID: oDJoKVkxMy2Qwp-Zw-AImw_1753770231 Received: from mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.93]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 0F6B2180048E; Tue, 29 Jul 2025 06:23:51 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.12]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id F1FFF18003FC; Tue, 29 Jul 2025 06:23:48 +0000 (UTC) Date: Tue, 29 Jul 2025 07:23:45 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Thomas Huth Cc: qemu-devel@nongnu.org, Michael Roth , Kostiantyn Kostiuk , qemu-trivial@nongnu.org Subject: Re: [PATCH] qga: Fix ubsan warning Message-ID: References: <20250728173016.314460-1-thuth@redhat.com> <1501b69c-6920-4319-bd8a-550243cb3daa@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1501b69c-6920-4319-bd8a-550243cb3daa@redhat.com> User-Agent: Mutt/2.2.14 (2025-02-20) X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 Received-SPF: pass client-ip=170.10.133.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-trivial@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Errors-To: qemu-trivial-bounces+qemu-trivial=archiver.kernel.org@nongnu.org Sender: qemu-trivial-bounces+qemu-trivial=archiver.kernel.org@nongnu.org On Tue, Jul 29, 2025 at 08:02:25AM +0200, Thomas Huth wrote: > On 28/07/2025 19.53, Daniel P. Berrangé wrote: > > On Mon, Jul 28, 2025 at 07:30:16PM +0200, Thomas Huth wrote: > > > From: Thomas Huth > > > > > > When compiling QEMU with --enable-ubsan there is a undefined behavior > > > warning when running "make check": > > > > > > .../qga/commands-linux.c:452:15: runtime error: applying non-zero offset 5 to null pointer > > > #0 0x55ea7b89450c in build_guest_fsinfo_for_pci_dev ..../qga/commands-linux.c:452:15 > > > > > > Add a check to avoid incrementing the NULL pointer here. > > > > > > Signed-off-by: Thomas Huth > > > --- > > > qga/commands-linux.c | 4 +++- > > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > > > diff --git a/qga/commands-linux.c b/qga/commands-linux.c > > > index 9e8a934b9a6..caf7c3ca22b 100644 > > > --- a/qga/commands-linux.c > > > +++ b/qga/commands-linux.c > > > @@ -449,7 +449,9 @@ static bool build_guest_fsinfo_for_pci_dev(char const *syspath, > > > has_ata = true; > > > } else { > > > p = strstr(syspath, "/host"); > > > - q = p + 5; > > > + if (p) { > > > + q = p + 5; > > > + } > > > } > > > if (p && sscanf(q, "%u", &host) == 1) { > > > > q is always non-NULL if p is non-NULL, so this is safe, but I would be more > > happy with this changing to 'q && sscanf' to eliminate the indirection. > > If we agree to do a bigger change here, I'd rather drop the "q" pointer > completely and use a new integer variable instead, something like: > > int offset; > ... > p = strstr(syspath, "/ata"); > if (p) { > offset = 4; > has_ata = true; > } else { > offset = 5; > p = strstr(syspath, "/host"); > } > if (p && sscanf(p + offset, "%u", &host) == 1) { > ... > } > > WDYT? Works for me. With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|