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=-6.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 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 F0895C433E8 for ; Tue, 28 Jul 2020 15:45:25 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id C0B9920A8B for ; Tue, 28 Jul 2020 15:45:25 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="fLJUuW24" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C0B9920A8B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:54134 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1k0RnA-0007UD-W5 for qemu-devel@archiver.kernel.org; Tue, 28 Jul 2020 11:45:25 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:53000) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1k0RmM-0006yj-Ly for qemu-devel@nongnu.org; Tue, 28 Jul 2020 11:44:34 -0400 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:58930 helo=us-smtp-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1k0RmK-0005TH-Gh for qemu-devel@nongnu.org; Tue, 28 Jul 2020 11:44:34 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1595951071; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=oX0MDNmbez7Vo9omv9rLXT2ENPzORxiz9rHy2FeZttw=; b=fLJUuW24VPtsnjCbZZ6FDZ7aTqwlA7Le1w2b6N0OGwLPazNJbebEgVzFk4pRU+TWbbnrMj pIFl0zHBCnhiLKH0ueNpNw6SDVjCPNGBFU3fQMHNLOryuLMQo1Gsey2o/49TFGZxnmjAoR 4Z1mp61EgtpbywIs3eMNqDis9As7YK0= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-37-wNmlRL1SMDqTEZ87Sj-Mjw-1; Tue, 28 Jul 2020 11:44:27 -0400 X-MC-Unique: wNmlRL1SMDqTEZ87Sj-Mjw-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 37D3D10CE790 for ; Tue, 28 Jul 2020 15:44:26 +0000 (UTC) Received: from [10.10.118.248] (ovpn-118-248.rdu2.redhat.com [10.10.118.248]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 27603726BE; Tue, 28 Jul 2020 15:44:22 +0000 (UTC) Subject: Re: Missing qapi_free_Type in error case for qapi generated code? To: Christophe de Dinechin , qemu-devel@nongnu.org References: From: Eric Blake Organization: Red Hat, Inc. Message-ID: Date: Tue, 28 Jul 2020 10:44:21 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=eblake@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=207.211.31.120; envelope-from=eblake@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/07/28 10:28:27 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, 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_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 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" On 7/28/20 10:26 AM, Christophe de Dinechin wrote: > The qapi generated code for qmp_marshal_query_spice seems to be missing a > resource deallocation for "retval". For example, for SpiceInfo: > > retval = qmp_query_spice(&err); > error_propagate(errp, err); > if (err) { > /* retval not freed here */ Because it should be NULL here. Returning an error AND an object is frowned on. > /* Missing: qapi_free_SpiceInfo(retval); */ > goto out; > } > > qmp_marshal_output_SpiceInfo(retval, ret, errp); And here, retval was non-NULL, but is cleaned as a side-effect of qmp_marshal_output_SpiceInfo. > > out: So no matter how you get to the label, retval is no longer valid memory that can be leaked. > visit_free(v); > v = qapi_dealloc_visitor_new(); > visit_start_struct(v, NULL, NULL, 0, NULL); > visit_end_struct(v, NULL); > visit_free(v); > } > #endif /* defined(CONFIG_SPICE) */ > > Questions: > > - Is the query code supposed to always return NULL in case of error? Yes. If not, that is a bug in qmp_query_spice. > In the > case of hmp_info_spice, there is no check for info==NULL, so on the > contrary, it seems to indicate that a non-null result is always expected, > and that function does call qapi_free_SpiceInfo Calling qapi_free_SpiceInfo(NULL) is a safe no-op. Or if you expect the function to always succeed, you could pass &error_abort as the errp parameter. > > - If not, is there an existing shortcut to generate the correct deallocation > code for return types that need it? You can't just use > qapi_free_%(c_type)s because that would generate an extra * character, > i.e. I get "SpiceInfo *" and not "SpiceInfo". Ah, you're debating about editing scripts/qapi/commands.py. If anything, an edit to add 'assert(!retval)' if qmp_COMMAND failed might be smarter than trying to add code to free retval. > > - If not, is there any good way to know if the type is a pointer type? > (A quick look in cripts/qapi/types.py does not show anything obvious) Look at scripts/qapi/schema.py; each QAPI metatype has implementations of .c_name and .c_type that determine how to represent that QAPI object in C. You probably want c_name instead of c_type when constructing the name of a qapi_free_FOO function, but that goes back to my question of whether such a call is even needed. -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org