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 AE5B3C3ABC9 for ; Fri, 9 May 2025 08:58:04 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1uDJXo-0001nP-9c; Fri, 09 May 2025 04:57:24 -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 1uDJXn-0001jX-4I for qemu-devel@nongnu.org; Fri, 09 May 2025 04:57:23 -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 1uDJXk-0007dz-Qf for qemu-devel@nongnu.org; Fri, 09 May 2025 04:57:22 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1746781039; h=from:from: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=2DFccFotjZvoovq6O2ud6WMUIsIoX0HGYwyovQBan+k=; b=GulsrjEdxjvLiW9SfT1VyYYdEm+CmtIj4ieQ0awj+RuSnTe4XRUxwZ5uQlCn6cE4wjAt3x XOXyliUcl9Gz1flr1LMI+nrxaZAR3dEVVYlhSBU4NkvsZvSXs4SscOZB8Bxskh34ANqk4X k5b9N+GJTyhF0p0mOEIcDHPCVSEcyq4= 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-516-dIcxlrAbM-W33GATAWWOJw-1; Fri, 09 May 2025 04:57:16 -0400 X-MC-Unique: dIcxlrAbM-W33GATAWWOJw-1 X-Mimecast-MFC-AGG-ID: dIcxlrAbM-W33GATAWWOJw_1746781035 Received: from mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.15]) (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 BC71F1800875; Fri, 9 May 2025 08:57:14 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.45.242.27]) by mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 462961955F24; Fri, 9 May 2025 08:57:14 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id A6A6821E66C2; Fri, 09 May 2025 10:57:11 +0200 (CEST) From: Markus Armbruster To: Daniel P. =?utf-8?Q?Berrang=C3=A9?= Cc: Nabih Estefan , qemu-devel@nongnu.org, richard.henderson@linaro.org, pbonzini@redhat.com, Peter Foley Subject: Re: [PATCH 1/2] util: fix msan findings in keyval In-Reply-To: ("Daniel P. =?utf-8?Q?Berrang?= =?utf-8?Q?=C3=A9=22's?= message of "Fri, 9 May 2025 08:58:07 +0100") References: <20250508222132.748479-1-nabihestefan@google.com> <20250508222132.748479-2-nabihestefan@google.com> <87cycibagm.fsf@pond.sub.org> Date: Fri, 09 May 2025 10:57:11 +0200 Message-ID: <87zffm6u1k.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.0 on 10.30.177.15 Received-SPF: pass client-ip=170.10.133.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -34 X-Spam_score: -3.5 X-Spam_bar: --- X-Spam_report: (-3.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1.416, 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_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Daniel P. Berrang=C3=A9 writes: > On Fri, May 09, 2025 at 07:48:57AM +0200, Markus Armbruster wrote: >> Nabih Estefan writes: >>=20 >> > From: Peter Foley >> > >> > e.g. >> > I 2025-02-28 09:51:05.240071-0800 624 stream.go:47 qemu: Uninitialize= d value was created by an allocation of 'key_in_cur.i' in the stack frame >> > I 2025-02-28 09:51:05.240187-0800 624 stream.go:47 qemu: #0 0xaaaac49= f489c in keyval_parse_one third_party/qemu/util/keyval.c:190:5 >> > >> > Signed-off-by: Peter Foley >> > Signed-off-by: Nabih Estefan >> > --- >> > util/keyval.c | 2 +- >> > 1 file changed, 1 insertion(+), 1 deletion(-) >> > >> > diff --git a/util/keyval.c b/util/keyval.c >> > index a70629a481..f33c64079d 100644 >> > --- a/util/keyval.c >> > +++ b/util/keyval.c >> > @@ -187,7 +187,7 @@ static const char *keyval_parse_one(QDict *qdict, = const char *params, >> > { >> > const char *key, *key_end, *val_end, *s, *end; >> > size_t len; >> > - char key_in_cur[128]; >> > + char key_in_cur[128] =3D {}; >> > QDict *cur; >> > int ret; >> > QObject *next; >>=20 >> Prior review of Peter's patch concluded this must be false positive: >> https://lore.kernel.org/qemu-devel/14168384-ecdb-4c05-8267-ac5ef1c46fe9@= redhat.com/ > > While I agree with Paolo's reasoning, I think it is still worth adding an > explicit initializer, because it makes it easier for both humans and mach= ines > to reason about correctless. I think the code is just fine as is. But if we decide we want an initializer to make things easier for casual readers / imperfect tools, then let's use "", not {}, as I suggested in my review. > To reinforce that we don't have an actual bug though, also note that qemu > unconditionally builds with -ftrivial-auto-var-init=3Dzero. So if we happ= en > to forget any, it won't cause a bug in the common case of a zero-initiali= zer. > > With regards, > Daniel