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=-13.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 DDE6AC07E99 for ; Mon, 5 Jul 2021 10:07:13 +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 99CB8613D1 for ; Mon, 5 Jul 2021 10:07:13 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 99CB8613D1 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]:42106 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1m0LVQ-0008Aw-Gu for qemu-devel@archiver.kernel.org; Mon, 05 Jul 2021 06:07:12 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:38606) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1m0LRS-0008On-Sz for qemu-devel@nongnu.org; Mon, 05 Jul 2021 06:03:06 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:41092) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1m0LRR-0000nW-76 for qemu-devel@nongnu.org; Mon, 05 Jul 2021 06:03:06 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1625479384; 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=wvQHA93JiGIpz1G0Cyy5ab5xSbhqVWLuEjlIwl7FZ/w=; b=XaF8pzqmBMez48JiciQ09CQYwl5lx8sJR2g0wW4Yv6ccM8g5RUVG31282DKOxrRnKYahWn 9zMTyRu/0T6NQsbyfyOP+abrmH3HrxHYL8HQpSwaViQdczGssz0qGefrO0PuDOFlpV1E+d M965okuhDWMUcIhDs2SxWJjuTiRtsxs= 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-28-GtPwuD9BOAax47BHEWKU1w-1; Mon, 05 Jul 2021 06:03:02 -0400 X-MC-Unique: GtPwuD9BOAax47BHEWKU1w-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 6F4CD100C610; Mon, 5 Jul 2021 10:03:01 +0000 (UTC) Received: from dgilbert-t580.localhost (ovpn-114-11.ams2.redhat.com [10.36.114.11]) by smtp.corp.redhat.com (Postfix) with ESMTP id 1F56860C0F; Mon, 5 Jul 2021 10:02:58 +0000 (UTC) From: "Dr. David Alan Gilbert (git)" To: qemu-devel@nongnu.org, berrange@redhat.com, linfeng23@huawei.com, groug@kaod.org, huangy81@chinatelecom.cn, lvivier@redhat.com, lizhijian@cn.fujitsu.com, peterx@redhat.com, vgoyal@redhat.com Subject: [PULL 02/19] migration: fix the memory overwriting risk in add_to_iovec Date: Mon, 5 Jul 2021 11:02:18 +0100 Message-Id: <20210705100235.157093-3-dgilbert@redhat.com> In-Reply-To: <20210705100235.157093-1-dgilbert@redhat.com> References: <20210705100235.157093-1-dgilbert@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dgilbert@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset="US-ASCII" Received-SPF: pass client-ip=170.10.133.124; envelope-from=dgilbert@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -42 X-Spam_score: -4.3 X-Spam_bar: ---- X-Spam_report: (-4.3 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1.441, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=-0.01, RCVD_IN_MSPIKE_WL=-0.01, 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: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: leobras@redhat.com, stefanha@redhat.com, quintela@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" From: Feng Lin When testing migration, a Segmentation fault qemu core is generated. 0 error_free (err=0x1) 1 0x00007f8b862df647 in qemu_fclose (f=f@entry=0x55e06c247640) 2 0x00007f8b8516d59a in migrate_fd_cleanup (s=s@entry=0x55e06c0e1ef0) 3 0x00007f8b8516d66c in migrate_fd_cleanup_bh (opaque=0x55e06c0e1ef0) 4 0x00007f8b8626a47f in aio_bh_poll (ctx=ctx@entry=0x55e06b5a16d0) 5 0x00007f8b8626e71f in aio_dispatch (ctx=0x55e06b5a16d0) 6 0x00007f8b8626a33d in aio_ctx_dispatch (source=, callback=, user_data=) 7 0x00007f8b866bdba4 in g_main_context_dispatch () 8 0x00007f8b8626cde9 in glib_pollfds_poll () 9 0x00007f8b8626ce62 in os_host_main_loop_wait (timeout=) 10 0x00007f8b8626cffd in main_loop_wait (nonblocking=nonblocking@entry=0) 11 0x00007f8b862ef01f in main_loop () Using gdb print the struct QEMUFile f = { ..., iovcnt = 65, last_error = 21984, last_error_obj = 0x1, shutdown = true } Well iovcnt is overflow, because the max size of MAX_IOV_SIZE is 64. struct QEMUFile { ...; struct iovec iov[MAX_IOV_SIZE]; unsigned int iovcnt; int last_error; Error *last_error_obj; bool shutdown; }; iovcnt and last_error is overwrited by add_to_iovec(). Right now, add_to_iovec() increase iovcnt before check the limit. And it seems that add_to_iovec() assumes that iovcnt will set to zero in qemu_fflush(). But qemu_fflush() will directly return when f->shutdown is true. The situation may occur when libvirtd restart during migration, after f->shutdown is set, before calling qemu_file_set_error() in qemu_file_shutdown(). So the safiest way is checking the iovcnt before increasing it. Signed-off-by: Feng Lin Message-Id: <20210625062138.1899-1-linfeng23@huawei.com> Reviewed-by: Dr. David Alan Gilbert Signed-off-by: Dr. David Alan Gilbert Fix typo in 'writeable' which is actually misnamed 'writable' --- migration/qemu-file.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/migration/qemu-file.c b/migration/qemu-file.c index d6e03dbc0e..1eacf9e831 100644 --- a/migration/qemu-file.c +++ b/migration/qemu-file.c @@ -416,6 +416,11 @@ static int add_to_iovec(QEMUFile *f, const uint8_t *buf, size_t size, { f->iov[f->iovcnt - 1].iov_len += size; } else { + if (f->iovcnt >= MAX_IOV_SIZE) { + /* Should only happen if a previous fflush failed */ + assert(f->shutdown || !qemu_file_is_writable(f)); + return 1; + } if (may_free) { set_bit(f->iovcnt, f->may_free); } -- 2.31.1