From patchwork Fri Dec 3 23:15:29 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Blake X-Patchwork-Id: 12655983 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 22200C433EF for ; Fri, 3 Dec 2021 23:21:41 +0000 (UTC) Received: from localhost ([::1]:59240 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mtHs4-0000A4-6P for qemu-devel@archiver.kernel.org; Fri, 03 Dec 2021 18:21:40 -0500 Received: from eggs.gnu.org ([209.51.188.92]:37580) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mtHmt-0007Rg-6L for qemu-devel@nongnu.org; Fri, 03 Dec 2021 18:16:22 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:36528) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mtHmk-00035E-JI for qemu-devel@nongnu.org; Fri, 03 Dec 2021 18:16:18 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1638573370; 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=ibcawdHRmUpfibv2B8Hsfyy1NTf7zArNMZpqL9nnHVc=; b=LMxVt9WWaJhjedIjDBN4LIcmjeESn5sFUMvFxwBdhofhijcvseR4yJdw5CXAijRRkV+Hwi ep5TNKaVs1GEsmXDRaNGKisNgLq0UCon14jbQMQI7w/x33iRyHf38lKD4fQJZoi0B827OE 9GI3GT/6H64kSmmICpzZ3GXFQa+NQfI= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-590-jfpZX-kXOIKrplRnXoXRow-1; Fri, 03 Dec 2021 18:16:06 -0500 X-MC-Unique: jfpZX-kXOIKrplRnXoXRow-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id E240E102C886; Fri, 3 Dec 2021 23:16:05 +0000 (UTC) Received: from blue.redhat.com (unknown [10.2.16.22]) by smtp.corp.redhat.com (Postfix) with ESMTP id BF2E15D9D5; Fri, 3 Dec 2021 23:15:59 +0000 (UTC) From: Eric Blake To: qemu-devel@nongnu.org Subject: [PATCH 04/14] nbd/client: Add safety check on chunk payload length Date: Fri, 3 Dec 2021 17:15:29 -0600 Message-Id: <20211203231539.3900865-5-eblake@redhat.com> In-Reply-To: <20211203231539.3900865-1-eblake@redhat.com> References: <20211203231307.wmtbw7r72tyzkkax@redhat.com> <20211203231539.3900865-1-eblake@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 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 Received-SPF: pass client-ip=170.10.133.124; envelope-from=eblake@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=-0.717, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable 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: , Cc: nsoffer@redhat.com, vsementsov@virtuozzo.com, libguestfs@redhat.com, qemu-block@nongnu.org, nbd@other.debian.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Our existing use of structured replies either reads into a qiov capped at 32M (NBD_CMD_READ) or caps allocation to 1000 bytes (see NBD_MAX_MALLOC_PAYLOAD in block/nbd.c). But the existing length checks are rather late; if we encounter a buggy (or malicious) server that sends a super-large payload length, we should drop the connection right then rather than assuming the layer on top will be careful. This becomes more important when we permit 64-bit lengths which are even more likely to have the potential for attempted denial of service abuse. Signed-off-by: Eric Blake Reviewed-by: Vladimir Sementsov-Ogievskiy --- nbd/client.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/nbd/client.c b/nbd/client.c index 30d5383cb195..8f137c2320bb 100644 --- a/nbd/client.c +++ b/nbd/client.c @@ -1412,6 +1412,18 @@ static int nbd_receive_structured_reply_chunk(QIOChannel *ioc, chunk->handle = be64_to_cpu(chunk->handle); chunk->length = be32_to_cpu(chunk->length); + /* + * Because we use BLOCK_STATUS with REQ_ONE, and cap READ requests + * at 32M, no valid server should send us payload larger than + * this. Even if we stopped using REQ_ONE, sane servers will cap + * the number of extents they return for block status. + */ + if (chunk->length > NBD_MAX_BUFFER_SIZE + sizeof(NBDStructuredReadData)) { + error_setg(errp, "server chunk %" PRIu32 " (%s) payload is too long", + chunk->type, nbd_rep_lookup(chunk->type)); + return -EINVAL; + } + return 0; }