File 0268-ui-track-how-much-decoded-data-we-c.patch of Package qemu-linux-user.15026

From 8e7a0a1c5f8942cadcb61e466524b52c9b20a5a7 Mon Sep 17 00:00:00 2001
From: "Daniel P. Berrange" <berrange@redhat.com>
Date: Mon, 18 Dec 2017 19:12:20 +0000
Subject: [PATCH] ui: track how much decoded data we consumed when doing SASL
 encoding
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When we encode data for writing with SASL, we encode the entire pending output
buffer. The subsequent write, however, may not be able to send the full encoded
data in one go though, particularly with a slow network. So we delay setting 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. So it
is not valid to set offset back to zero. Instead we must keep track of how 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 problem
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 <berrange@redhat.com>
Reviewed-by: Darren Kenny <darren.kenny@oracle.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-id: 20171218191228.31018-6-berrange@redhat.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
(cherry picked from commit 8f61f1c5a6bc06438a1172efa80bc7606594fa07)
[LY: BSC#1073489]
Signed-off-by: Liang Yan <lyan@suse.com>
---
 ui/vnc-auth-sasl.c | 3 ++-
 ui/vnc-auth-sasl.h | 1 +
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/ui/vnc-auth-sasl.c b/ui/vnc-auth-sasl.c
index 5ae29c14cf..d86a63d7af 100644
--- a/ui/vnc-auth-sasl.c
+++ b/ui/vnc-auth-sasl.c
@@ -66,6 +66,7 @@ long vnc_client_write_sasl(VncState *vs)
         if (err != SASL_OK)
             return vnc_client_io_error(vs, -1, NULL);
 
+        vs->sasl.encodedRawLength = vs->output.offset;
         vs->sasl.encodedOffset = 0;
     }
 
@@ -77,7 +78,7 @@ long vnc_client_write_sasl(VncState *vs)
 
     vs->sasl.encodedOffset += ret;
     if (vs->sasl.encodedOffset == vs->sasl.encodedLength) {
-        vs->output.offset = 0;
+        vs->output.offset -= vs->sasl.encodedRawLength;
         vs->sasl.encoded = NULL;
         vs->sasl.encodedOffset = vs->sasl.encodedLength = 0;
     }
diff --git a/ui/vnc-auth-sasl.h b/ui/vnc-auth-sasl.h
index 3f59da67eb..47a847ef56 100644
--- a/ui/vnc-auth-sasl.h
+++ b/ui/vnc-auth-sasl.h
@@ -55,6 +55,7 @@ struct VncStateSASL {
      */
     const uint8_t *encoded;
     unsigned int encodedLength;
+    unsigned int encodedRawLength;
     unsigned int encodedOffset;
     char *username;
     char *mechlist;