From patchwork Wed Feb 22 16:01:17 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Halil Pasic X-Patchwork-Id: 9587069 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 9C442600CA for ; Wed, 22 Feb 2017 16:02:17 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 8BCFA28484 for ; Wed, 22 Feb 2017 16:02:17 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 80C082857B; Wed, 22 Feb 2017 16:02:17 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 047E528484 for ; Wed, 22 Feb 2017 16:02:17 +0000 (UTC) Received: from localhost ([::1]:53307 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cgZMu-0005Oq-1k for patchwork-qemu-devel@patchwork.kernel.org; Wed, 22 Feb 2017 11:02:16 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:34881) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cgZMH-0005MH-Ej for qemu-devel@nongnu.org; Wed, 22 Feb 2017 11:01:38 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cgZMD-0002tr-DV for qemu-devel@nongnu.org; Wed, 22 Feb 2017 11:01:37 -0500 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:59366) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1cgZMD-0002tG-4g for qemu-devel@nongnu.org; Wed, 22 Feb 2017 11:01:33 -0500 Received: from pps.filterd (m0098404.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.20/8.16.0.20) with SMTP id v1MFwdWu033935 for ; Wed, 22 Feb 2017 11:01:32 -0500 Received: from e06smtp08.uk.ibm.com (e06smtp08.uk.ibm.com [195.75.94.104]) by mx0a-001b2d01.pphosted.com with ESMTP id 28scvp39qs-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Wed, 22 Feb 2017 11:01:31 -0500 Received: from localhost by e06smtp08.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; Wed, 22 Feb 2017 16:01:25 -0000 Received: from b06cxnps4074.portsmouth.uk.ibm.com (d06relay11.portsmouth.uk.ibm.com [9.149.109.196]) by d06dlp01.portsmouth.uk.ibm.com (Postfix) with ESMTP id B1B9F17D805A; Wed, 22 Feb 2017 16:04:35 +0000 (GMT) Received: from d06av26.portsmouth.uk.ibm.com (d06av26.portsmouth.uk.ibm.com [9.149.105.62]) by b06cxnps4074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id v1MG1PMu2490686; Wed, 22 Feb 2017 16:01:25 GMT Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id C82F8AE063; Wed, 22 Feb 2017 14:59:15 +0000 (GMT) Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 89618AE064; Wed, 22 Feb 2017 14:59:15 +0000 (GMT) Received: from tuxmaker.boeblingen.de.ibm.com (unknown [9.152.85.9]) by d06av26.portsmouth.uk.ibm.com (Postfix) with ESMTPS; Wed, 22 Feb 2017 14:59:15 +0000 (GMT) From: Halil Pasic To: qemu-devel@nongnu.org, "Dr. David Alan Gilbert" Date: Wed, 22 Feb 2017 17:01:17 +0100 X-Mailer: git-send-email 2.8.4 In-Reply-To: <20170222160119.52771-1-pasic@linux.vnet.ibm.com> References: <20170222160119.52771-1-pasic@linux.vnet.ibm.com> X-TM-AS-GCONF: 00 X-Content-Scanned: Fidelis XPS MAILER x-cbid: 17022216-0032-0000-0000-00000722E778 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17022216-0033-0000-0000-000023870A81 Message-Id: <20170222160119.52771-4-pasic@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:, , definitions=2017-02-22_10:, , signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1612050000 definitions=main-1702220150 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x [generic] [fuzzy] X-Received-From: 148.163.156.1 Subject: [Qemu-devel] [PATCH v2 3/5] migration/vmstate: fix array of ptr with nullptrs X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Amit Shah , Halil Pasic , Juan Quintela Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" X-Virus-Scanned: ClamAV using ClamSMTP Make VMS_ARRAY_OF_POINTER cope with null pointers. Previously the reward for trying to migrate an array with some null pointers in it was an illegal memory access, that is a swift and painless death of the process. Let's make vmstate cope with this scenario. The general approach is, when we encounter a null pointer (element), instead of following the pointer to save/load the data behind it, we save/load a placeholder. This way we can detect if we expected a null pointer at the load side but not null data was saved instead. Signed-off-by: Halil Pasic Reviewed-by: Guenther Hutzl Reviewed-by: Dr. David Alan Gilbert --- We will need this to load/save some on demand created state in the (s390x) channel subsystem (see ChannelSubSys.css in hw/s390x/css.c for an example). --- include/migration/vmstate.h | 4 ++++ migration/vmstate.c | 40 ++++++++++++++++++++++++++++++++++++++-- 2 files changed, 42 insertions(+), 2 deletions(-) diff --git a/include/migration/vmstate.h b/include/migration/vmstate.h index 63e7b02..f2dbf84 100644 --- a/include/migration/vmstate.h +++ b/include/migration/vmstate.h @@ -253,6 +253,10 @@ extern const VMStateInfo vmstate_info_uint16; extern const VMStateInfo vmstate_info_uint32; extern const VMStateInfo vmstate_info_uint64; +/** Put this in the stream when migrating a null pointer.*/ +#define VMS_NULLPTR_MARKER (0x30U) /* '0' */ +extern const VMStateInfo vmstate_info_nullptr; + extern const VMStateInfo vmstate_info_float64; extern const VMStateInfo vmstate_info_cpudouble; diff --git a/migration/vmstate.c b/migration/vmstate.c index 836a7a4..78b3cd4 100644 --- a/migration/vmstate.c +++ b/migration/vmstate.c @@ -117,7 +117,11 @@ int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd, if (field->flags & VMS_ARRAY_OF_POINTER) { curr_elem = *(void **)curr_elem; } - if (field->flags & VMS_STRUCT) { + if (!curr_elem) { + /* if null pointer check placeholder and do not follow */ + assert(field->flags & VMS_ARRAY_OF_POINTER); + ret = vmstate_info_nullptr.get(f, curr_elem, size, NULL); + } else if (field->flags & VMS_STRUCT) { ret = vmstate_load_state(f, field->vmsd, curr_elem, field->vmsd->version_id); } else { @@ -332,7 +336,11 @@ void vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd, assert(curr_elem); curr_elem = *(void **)curr_elem; } - if (field->flags & VMS_STRUCT) { + if (!curr_elem) { + /* if null pointer write placeholder and do not follow */ + assert(field->flags & VMS_ARRAY_OF_POINTER); + vmstate_info_nullptr.put(f, curr_elem, size, NULL, NULL); + } else if (field->flags & VMS_STRUCT) { vmstate_save_state(f, field->vmsd, curr_elem, vmdesc_loop); } else { field->info->put(f, curr_elem, size, field, vmdesc_loop); @@ -747,6 +755,34 @@ const VMStateInfo vmstate_info_uint64 = { .put = put_uint64, }; +static int get_nullptr(QEMUFile *f, void *pv, size_t size, VMStateField *field) + +{ + if (qemu_get_byte(f) == VMS_NULLPTR_MARKER) { + return 0; + } + error_report("vmstate: get_nullptr expected VMS_NULLPTR_MARKER"); + return -EINVAL; +} + +static int put_nullptr(QEMUFile *f, void *pv, size_t size, + VMStateField *field, QJSON *vmdesc) + +{ + if (pv == NULL) { + qemu_put_byte(f, VMS_NULLPTR_MARKER); + return 0; + } + error_report("vmstate: put_nullptr must be called with pv == NULL"); + return -EINVAL; +} + +const VMStateInfo vmstate_info_nullptr = { + .name = "uint64", + .get = get_nullptr, + .put = put_nullptr, +}; + /* 64 bit unsigned int. See that the received value is the same than the one in the field */