From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:55479) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1alwbo-0000LW-Er for qemu-devel@nongnu.org; Fri, 01 Apr 2016 06:47:21 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1alwbl-0002ir-8X for qemu-devel@nongnu.org; Fri, 01 Apr 2016 06:47:20 -0400 Received: from mx1.redhat.com ([209.132.183.28]:56884) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1alwbl-0002if-3A for qemu-devel@nongnu.org; Fri, 01 Apr 2016 06:47:17 -0400 Received: from int-mx14.intmail.prod.int.phx2.redhat.com (int-mx14.intmail.prod.int.phx2.redhat.com [10.5.11.27]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id CFC117F0A0 for ; Fri, 1 Apr 2016 10:47:15 +0000 (UTC) References: <1459459222-8637-1-git-send-email-eblake@redhat.com> <1459459222-8637-4-git-send-email-eblake@redhat.com> From: Paolo Bonzini Message-ID: <56FE51AF.1030809@redhat.com> Date: Fri, 1 Apr 2016 12:47:11 +0200 MIME-Version: 1.0 In-Reply-To: <1459459222-8637-4-git-send-email-eblake@redhat.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 3/3] nbd: Reject unknown request flags List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Eric Blake , qemu-devel@nongnu.org On 31/03/2016 23:20, Eric Blake wrote: > The NBD protocol says that clients should not send a command flag > that has not been negotiated (whether by the client requesting an > option during a handshake, or because we advertise support for the > flag in response to NBD_OPT_EXPORT_NAME), and that servers should > reject invalid flags with EINVAL. We were silently ignoring the > flags instead. The client can't rely on our behavior, since it is > their fault for passing the bad flag in the first place, but it's > better to be robust up front than to possibly behave differently > than the client was expecting with the attempted flag. > > Signed-off-by: Eric Blake > --- > nbd/server.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/nbd/server.c b/nbd/server.c > index a590773..31bd9c5 100644 > --- a/nbd/server.c > +++ b/nbd/server.c > @@ -974,6 +974,10 @@ static ssize_t nbd_co_receive_request(NBDRequest *req, struct nbd_request *reque > goto out; > } > > + if (request->flags & ~NBD_CMD_FLAG_FUA) { > + LOG("unsupported flags (got 0x%x)", request->flags); > + return -EINVAL; > + } > if ((request->from + request->len) < request->from) { > LOG("integer overflow detected! " > "you're probably being attacked"); > Queued for 2.6. Paolo