From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:48323) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eZyvG-0003NR-Mx for qemu-devel@nongnu.org; Fri, 12 Jan 2018 07:59:08 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eZyvF-0002pM-JR for qemu-devel@nongnu.org; Fri, 12 Jan 2018 07:59:02 -0500 Received: from mx1.redhat.com ([209.132.183.28]:54194) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1eZyvF-0002oJ-DQ for qemu-devel@nongnu.org; Fri, 12 Jan 2018 07:59:01 -0500 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 mx1.redhat.com (Postfix) with ESMTPS id 7D6F6C0272F6 for ; Fri, 12 Jan 2018 12:59:00 +0000 (UTC) From: Gerd Hoffmann Date: Fri, 12 Jan 2018 13:58:46 +0100 Message-Id: <20180112125854.18261-7-kraxel@redhat.com> In-Reply-To: <20180112125854.18261-1-kraxel@redhat.com> References: <20180112125854.18261-1-kraxel@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Subject: [Qemu-devel] [PULL 06/14] ui: track how much decoded data we consumed when doing SASL encoding List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: "Daniel P. Berrange" , Gerd Hoffmann From: "Daniel P. Berrange" When we encode data for writing with SASL, we encode the entire pending o= utput buffer. The subsequent write, however, may not be able to send the full e= ncoded data in one go though, particularly with a slow network. So we delay sett= ing the output buffer offset back to zero until all the SASL encoded data is sent= . Between encoding the data and completing sending of the SASL encoded data= , however, more data might have been placed on the pending output buffer. S= o it is not valid to set offset back to zero. Instead we must keep track of ho= w much data we consumed during encoding and subtract only that amount. With the current bug we would be throwing away some pending data without = having sent it at all. By sheer luck this did not previously cause any serious p= roblem because appending data to the send buffer is always an atomic action, so = we only ever throw away complete RFB protocol messages. In the case of frame= buffer updates we'd catch up fairly quickly, so no obvious problem was visible. Signed-off-by: Daniel P. Berrange Reviewed-by: Darren Kenny Reviewed-by: Marc-Andr=C3=A9 Lureau Message-id: 20171218191228.31018-6-berrange@redhat.com Signed-off-by: Gerd Hoffmann --- ui/vnc-auth-sasl.h | 1 + ui/vnc-auth-sasl.c | 3 ++- 2 files changed, 3 insertions(+), 1 deletion(-) diff --git a/ui/vnc-auth-sasl.h b/ui/vnc-auth-sasl.h index cb42745a6b..b9d8de1c10 100644 --- a/ui/vnc-auth-sasl.h +++ b/ui/vnc-auth-sasl.h @@ -53,6 +53,7 @@ struct VncStateSASL { */ const uint8_t *encoded; unsigned int encodedLength; + unsigned int encodedRawLength; unsigned int encodedOffset; char *username; char *mechlist; diff --git a/ui/vnc-auth-sasl.c b/ui/vnc-auth-sasl.c index 23f28280e7..761493b9b2 100644 --- a/ui/vnc-auth-sasl.c +++ b/ui/vnc-auth-sasl.c @@ -67,6 +67,7 @@ long vnc_client_write_sasl(VncState *vs) if (err !=3D SASL_OK) return vnc_client_io_error(vs, -1, NULL); =20 + vs->sasl.encodedRawLength =3D vs->output.offset; vs->sasl.encodedOffset =3D 0; } =20 @@ -78,7 +79,7 @@ long vnc_client_write_sasl(VncState *vs) =20 vs->sasl.encodedOffset +=3D ret; if (vs->sasl.encodedOffset =3D=3D vs->sasl.encodedLength) { - vs->output.offset =3D 0; + vs->output.offset -=3D vs->sasl.encodedRawLength; vs->sasl.encoded =3D NULL; vs->sasl.encodedOffset =3D vs->sasl.encodedLength =3D 0; } --=20 2.9.3