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 849E4C3DA6E for ; Mon, 8 Jan 2024 12:35:48 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1rMoq8-0008DY-Pb; Mon, 08 Jan 2024 07:34:48 -0500 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 1rMoq6-0008CS-3z for qemu-devel@nongnu.org; Mon, 08 Jan 2024 07:34:46 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rMoq3-0003xx-5r for qemu-devel@nongnu.org; Mon, 08 Jan 2024 07:34:44 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1704717281; 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=jJxmxAScyvhTcm/ebk3qt2FehYaTMJcsAp7R41TQZRo=; b=TO7jSZxOsT+1vcmb2TOSQAyr2vSLpH5vm0t+vSbrvf73QDnZbS+Q01AkfkEimdU7xG5a4T 7O6DBsnA1weU02mYX+VeF/UHds9+vMOFQaNbh45EVvFQtDvJbfsyhsl8jk0nRLoaMT3j3E jMQlMIlaqd6G/BCArpkca/CCcj2KmG8= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-647-q76f6NCXNV2LywH_Qy06EQ-1; Mon, 08 Jan 2024 07:34:34 -0500 X-MC-Unique: q76f6NCXNV2LywH_Qy06EQ-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (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 mimecast-mx02.redhat.com (Postfix) with ESMTPS id 2968C1C2B660; Mon, 8 Jan 2024 12:34:34 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.39.192.71]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 080885190; Mon, 8 Jan 2024 12:34:34 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id A267821E6682; Mon, 8 Jan 2024 13:34:31 +0100 (CET) From: Markus Armbruster To: Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= Cc: Avihai Horon , qemu-devel@nongnu.org, Juan Quintela , Peter Xu , Fabiano Rosas , Leonardo Bras , Li Zhijian Subject: Re: [PATCH 09/11] migration: Fix migration_channel_read_peek() error path In-Reply-To: ("Philippe =?utf-8?Q?Mathieu-Daud=C3=A9=22's?= message of "Tue, 2 Jan 2024 11:05:56 +0100") References: <20231231093016.14204-1-avihaih@nvidia.com> <20231231093016.14204-10-avihaih@nvidia.com> Date: Mon, 08 Jan 2024 13:34:31 +0100 Message-ID: <87edest354.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 3.4.1 on 10.11.54.5 Received-SPF: pass client-ip=170.10.129.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -43 X-Spam_score: -4.4 X-Spam_bar: ---- X-Spam_report: (-4.4 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-2.243, 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_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 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 Philippe Mathieu-Daud=C3=A9 writes: > +Markus > > On 31/12/23 10:30, Avihai Horon wrote: >> migration_channel_read_peek() calls qio_channel_readv_full() and handles >> both cases of return value =3D=3D 0 and return value < 0 the same way, by >> calling error_setg() with errp. However, if return value < 0, errp is >> already set, so calling error_setg() with errp will lead to an assert. > > I suppose the API would be safer by passing &len as argument and > return a boolean. Doubtful, unless I'm misunderstanding something. Function comment: * Returns: the number of bytes read, or -1 on error, * or QIO_CHANNEL_ERR_BLOCK if no data is available * and the channel is non-blocking I understand this as: * Success case: return #bytes read * Error case: return -1, @errp is set * Would block case: return QIO_CHANNEL_ERR_BLOCK A zero return value must be the success case. I figure this can happen only at EOF. A caller might need to treat unexpected EOF as an error. >> Fix it by handling these cases separately, calling error_setg() with >> errp only in return value =3D=3D 0 case. >> Fixes: 6720c2b32725 ("migration: check magic value for deciding the mapp= ing of channels") >> Signed-off-by: Avihai Horon >> --- >> migration/channel.c | 9 ++++++--- >> 1 file changed, 6 insertions(+), 3 deletions(-) >> diff --git a/migration/channel.c b/migration/channel.c >> index ca3319a309..f9de064f3b 100644 >> --- a/migration/channel.c >> +++ b/migration/channel.c >> @@ -117,9 +117,12 @@ int migration_channel_read_peek(QIOChannel *ioc, >> len =3D qio_channel_readv_full(ioc, &iov, 1, NULL, NULL, >> QIO_CHANNEL_READ_FLAG_MSG_PEEK, er= rp); >> - if (len <=3D 0 && len !=3D QIO_CHANNEL_ERR_BLOCK) { >> - error_setg(errp, >> - "Failed to peek at channel"); >> + if (len < 0 && len !=3D QIO_CHANNEL_ERR_BLOCK) { >> + return -1; >> + } >> + >> + if (len =3D=3D 0) { >> + error_setg(errp, "Failed to peek at channel"); >> return -1; >> } > > Reviewed-by: Philippe Mathieu-Daud=C3=A9