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From 87a76b97164685ea1e1aaab6a35bfbaf18c60366 Mon Sep 17 00:00:00 2001
From: jmaloy <jmaloy@redhat.com>
Date: Mon, 25 May 2020 21:20:00 -0400
Subject: [PATCH] vnc: fix memory leak when vnc disconnect
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

RH-Author: jmaloy <jmaloy@redhat.com>
Message-id: <20200525212000.355756-2-jmaloy@redhat.com>
Patchwork-id: 96752
O-Subject: [RHEL-7.9 qemu-kvm PATCH v2 1/1] vnc: fix memory leak when vnc disconnect
Bugzilla: 1810408
RH-Acked-by: Gerd Hoffmann <kraxel@redhat.com>
RH-Acked-by: Daniel P. Berrange <berrange@redhat.com>
RH-Acked-by: Philippe Mathieu-Daudé <philmd@redhat.com>

From: Li Qiang <liq3ea@163.com>

Currently when qemu receives a vnc connect, it creates a 'VncState' to
represent this connection. In 'vnc_worker_thread_loop' it creates a
local 'VncState'. The connection 'VcnState' and local 'VncState' exchange
data in 'vnc_async_encoding_start' and 'vnc_async_encoding_end'.
In 'zrle_compress_data' it calls 'deflateInit2' to allocate the libz library
opaque data. The 'VncState' used in 'zrle_compress_data' is the local
'VncState'. In 'vnc_zrle_clear' it calls 'deflateEnd' to free the libz
library opaque data. The 'VncState' used in 'vnc_zrle_clear' is the connection
'VncState'. In currently implementation there will be a memory leak when the
vnc disconnect. Following is the asan output backtrack:

Direct leak of 29760 byte(s) in 5 object(s) allocated from:
    0 0xffffa67ef3c3 in __interceptor_calloc (/lib64/libasan.so.4+0xd33c3)
    1 0xffffa65071cb in g_malloc0 (/lib64/libglib-2.0.so.0+0x571cb)
    2 0xffffa5e968f7 in deflateInit2_ (/lib64/libz.so.1+0x78f7)
    3 0xaaaacec58613 in zrle_compress_data ui/vnc-enc-zrle.c:87
    4 0xaaaacec58613 in zrle_send_framebuffer_update ui/vnc-enc-zrle.c:344
    5 0xaaaacec34e77 in vnc_send_framebuffer_update ui/vnc.c:919
    6 0xaaaacec5e023 in vnc_worker_thread_loop ui/vnc-jobs.c:271
    7 0xaaaacec5e5e7 in vnc_worker_thread ui/vnc-jobs.c:340
    8 0xaaaacee4d3c3 in qemu_thread_start util/qemu-thread-posix.c:502
    9 0xffffa544e8bb in start_thread (/lib64/libpthread.so.0+0x78bb)
    10 0xffffa53965cb in thread_start (/lib64/libc.so.6+0xd55cb)

This is because the opaque allocated in 'deflateInit2' is not freed in
'deflateEnd'. The reason is that the 'deflateEnd' calls 'deflateStateCheck'
and in the latter will check whether 's->strm != strm'(libz's data structure).
This check will be true so in 'deflateEnd' it just return 'Z_STREAM_ERROR' and
not free the data allocated in 'deflateInit2'.

The reason this happens is that the 'VncState' contains the whole 'VncZrle',
so when calling 'deflateInit2', the 's->strm' will be the local address.
So 's->strm != strm' will be true.

To fix this issue, we need to make 'zrle' of 'VncState' to be a pointer.
Then the connection 'VncState' and local 'VncState' exchange mechanism will
work as expection. The 'tight' of 'VncState' has the same issue, let's also turn
it to a pointer.

Reported-by: Ying Fang <fangying1@huawei.com>
Signed-off-by: Li Qiang <liq3ea@163.com>
Message-id: 20190831153922.121308-1-liq3ea@163.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

(cherry picked from commit 6bf21f3d83e95bcc4ba35a7a07cc6655e8b010b0)
Manually re-adapted, since there has been a huge number of conflicting
commits applied upsteam since this code version. The re-adapted commit
was still very similar to the upstream one in the end.

Signed-off-by: Jon Maloy <jmaloy@redhat.com>
Signed-off-by: Jon Maloy <jmaloy.redhat.com>
---
 ui/vnc-enc-tight.c         | 219 +++++++++++++++++++------------------
 ui/vnc-enc-zlib.c          |  11 +-
 ui/vnc-enc-zrle-template.c |   2 +-
 ui/vnc-enc-zrle.c          |  68 ++++++------
 ui/vnc.c                   |  12 +-
 ui/vnc.h                   |   4 +-
 6 files changed, 162 insertions(+), 154 deletions(-)

diff --git a/ui/vnc-enc-tight.c b/ui/vnc-enc-tight.c
index e6966aebc3..f01375d5ef 100644
--- a/ui/vnc-enc-tight.c
+++ b/ui/vnc-enc-tight.c
@@ -119,7 +119,7 @@ static int send_png_rect(VncState *vs, int x, int y, int w, int h,
 
 static bool tight_can_send_png_rect(VncState *vs, int w, int h)
 {
-    if (vs->tight.type != VNC_ENCODING_TIGHT_PNG) {
+    if (vs->tight->type != VNC_ENCODING_TIGHT_PNG) {
         return false;
     }
 
@@ -147,7 +147,7 @@ tight_detect_smooth_image24(VncState *vs, int w, int h)
     int pixels = 0;
     int pix, left[3];
     unsigned int errors;
-    unsigned char *buf = vs->tight.tight.buffer;
+    unsigned char *buf = vs->tight->tight.buffer;
 
     /*
      * If client is big-endian, color samples begin from the second
@@ -214,7 +214,7 @@ tight_detect_smooth_image24(VncState *vs, int w, int h)
         int pixels = 0;                                                 \
         int sample, sum, left[3];                                       \
         unsigned int errors;                                            \
-        unsigned char *buf = vs->tight.tight.buffer;                    \
+        unsigned char *buf = vs->tight->tight.buffer;                    \
                                                                         \
         endian = 0; /* FIXME: ((vs->clientds.flags & QEMU_BIG_ENDIAN_FLAG) != \
                       (vs->ds->surface->flags & QEMU_BIG_ENDIAN_FLAG)); */ \
@@ -294,8 +294,8 @@ static int
 tight_detect_smooth_image(VncState *vs, int w, int h)
 {
     unsigned int errors;
-    int compression = vs->tight.compression;
-    int quality = vs->tight.quality;
+    int compression = vs->tight->compression;
+    int quality = vs->tight->quality;
 
     if (!vs->vd->lossy) {
         return 0;
@@ -307,7 +307,7 @@ tight_detect_smooth_image(VncState *vs, int w, int h)
         return 0;
     }
 
-    if (vs->tight.quality != (uint8_t)-1) {
+    if (vs->tight->quality != (uint8_t)-1) {
         if (w * h < VNC_TIGHT_JPEG_MIN_RECT_SIZE) {
             return 0;
         }
@@ -318,9 +318,9 @@ tight_detect_smooth_image(VncState *vs, int w, int h)
     }
 
     if (vs->client_pf.bytes_per_pixel == 4) {
-        if (vs->tight.pixel24) {
+        if (vs->tight->pixel24) {
             errors = tight_detect_smooth_image24(vs, w, h);
-            if (vs->tight.quality != (uint8_t)-1) {
+            if (vs->tight->quality != (uint8_t)-1) {
                 return (errors < tight_conf[quality].jpeg_threshold24);
             }
             return (errors < tight_conf[compression].gradient_threshold24);
@@ -350,7 +350,7 @@ tight_detect_smooth_image(VncState *vs, int w, int h)
         uint##bpp##_t c0, c1, ci;                                       \
         int i, n0, n1;                                                  \
                                                                         \
-        data = (uint##bpp##_t *)vs->tight.tight.buffer;                 \
+        data = (uint##bpp##_t *)vs->tight->tight.buffer;                \
                                                                         \
         c0 = data[0];                                                   \
         i = 1;                                                          \
@@ -421,9 +421,9 @@ static int tight_fill_palette(VncState *vs, int x, int y,
 {
     int max;
 
-    max = count / tight_conf[vs->tight.compression].idx_max_colors_divisor;
+    max = count / tight_conf[vs->tight->compression].idx_max_colors_divisor;
     if (max < 2 &&
-        count >= tight_conf[vs->tight.compression].mono_min_rect_size) {
+        count >= tight_conf[vs->tight->compression].mono_min_rect_size) {
         max = 2;
     }
     if (max >= 256) {
@@ -555,7 +555,7 @@ tight_filter_gradient24(VncState *vs, uint8_t *buf, int w, int h)
     int x, y, c;
 
     buf32 = (uint32_t *)buf;
-    memset(vs->tight.gradient.buffer, 0, w * 3 * sizeof(int));
+    memset(vs->tight->gradient.buffer, 0, w * 3 * sizeof(int));
 
     if (1 /* FIXME: (vs->clientds.flags & QEMU_BIG_ENDIAN_FLAG) ==
              (vs->ds->surface->flags & QEMU_BIG_ENDIAN_FLAG) */) {
@@ -573,7 +573,7 @@ tight_filter_gradient24(VncState *vs, uint8_t *buf, int w, int h)
             upper[c] = 0;
             here[c] = 0;
         }
-        prev = (int *)vs->tight.gradient.buffer;
+        prev = (int *)vs->tight->gradient.buffer;
         for (x = 0; x < w; x++) {
             pix32 = *buf32++;
             for (c = 0; c < 3; c++) {
@@ -613,7 +613,7 @@ tight_filter_gradient24(VncState *vs, uint8_t *buf, int w, int h)
         int prediction;                                                 \
         int x, y, c;                                                    \
                                                                         \
-        memset (vs->tight.gradient.buffer, 0, w * 3 * sizeof(int));     \
+        memset(vs->tight->gradient.buffer, 0, w * 3 * sizeof(int));     \
                                                                         \
         endian = 0; /* FIXME: ((vs->clientds.flags & QEMU_BIG_ENDIAN_FLAG) != \
                        (vs->ds->surface->flags & QEMU_BIG_ENDIAN_FLAG)); */ \
@@ -630,7 +630,7 @@ tight_filter_gradient24(VncState *vs, uint8_t *buf, int w, int h)
                 upper[c] = 0;                                           \
                 here[c] = 0;                                            \
             }                                                           \
-            prev = (int *)vs->tight.gradient.buffer;                    \
+            prev = (int *)vs->tight->gradient.buffer;                    \
             for (x = 0; x < w; x++) {                                   \
                 pix = *buf;                                             \
                 if (endian) {                                           \
@@ -786,7 +786,7 @@ static void extend_solid_area(VncState *vs, int x, int y, int w, int h,
 static int tight_init_stream(VncState *vs, int stream_id,
                              int level, int strategy)
 {
-    z_streamp zstream = &vs->tight.stream[stream_id];
+    z_streamp zstream = &vs->tight->stream[stream_id];
 
     if (zstream->opaque == NULL) {
         int err;
@@ -804,15 +804,15 @@ static int tight_init_stream(VncState *vs, int stream_id,
             return -1;
         }
 
-        vs->tight.levels[stream_id] = level;
+        vs->tight->levels[stream_id] = level;
         zstream->opaque = vs;
     }
 
-    if (vs->tight.levels[stream_id] != level) {
+    if (vs->tight->levels[stream_id] != level) {
         if (deflateParams(zstream, level, strategy) != Z_OK) {
             return -1;
         }
-        vs->tight.levels[stream_id] = level;
+        vs->tight->levels[stream_id] = level;
     }
     return 0;
 }
@@ -840,11 +840,11 @@ static void tight_send_compact_size(VncState *vs, size_t len)
 static int tight_compress_data(VncState *vs, int stream_id, size_t bytes,
                                int level, int strategy)
 {
-    z_streamp zstream = &vs->tight.stream[stream_id];
+    z_streamp zstream = &vs->tight->stream[stream_id];
     int previous_out;
 
     if (bytes < VNC_TIGHT_MIN_TO_COMPRESS) {
-        vnc_write(vs, vs->tight.tight.buffer, vs->tight.tight.offset);
+        vnc_write(vs, vs->tight->tight.buffer, vs->tight->tight.offset);
         return bytes;
     }
 
@@ -853,13 +853,13 @@ static int tight_compress_data(VncState *vs, int stream_id, size_t bytes,
     }
 
     /* reserve memory in output buffer */
-    buffer_reserve(&vs->tight.zlib, bytes + 64);
+    buffer_reserve(&vs->tight->zlib, bytes + 64);
 
     /* set pointers */
-    zstream->next_in = vs->tight.tight.buffer;
-    zstream->avail_in = vs->tight.tight.offset;
-    zstream->next_out = vs->tight.zlib.buffer + vs->tight.zlib.offset;
-    zstream->avail_out = vs->tight.zlib.capacity - vs->tight.zlib.offset;
+    zstream->next_in = vs->tight->tight.buffer;
+    zstream->avail_in = vs->tight->tight.offset;
+    zstream->next_out = vs->tight->zlib.buffer + vs->tight->zlib.offset;
+    zstream->avail_out = vs->tight->zlib.capacity - vs->tight->zlib.offset;
     previous_out = zstream->avail_out;
     zstream->data_type = Z_BINARY;
 
@@ -869,14 +869,14 @@ static int tight_compress_data(VncState *vs, int stream_id, size_t bytes,
         return -1;
     }
 
-    vs->tight.zlib.offset = vs->tight.zlib.capacity - zstream->avail_out;
+    vs->tight->zlib.offset = vs->tight->zlib.capacity - zstream->avail_out;
     /* ...how much data has actually been produced by deflate() */
     bytes = previous_out - zstream->avail_out;
 
     tight_send_compact_size(vs, bytes);
-    vnc_write(vs, vs->tight.zlib.buffer, bytes);
+    vnc_write(vs, vs->tight->zlib.buffer, bytes);
 
-    buffer_reset(&vs->tight.zlib);
+    buffer_reset(&vs->tight->zlib);
 
     return bytes;
 }
@@ -928,16 +928,17 @@ static int send_full_color_rect(VncState *vs, int x, int y, int w, int h)
 
     vnc_write_u8(vs, stream << 4); /* no flushing, no filter */
 
-    if (vs->tight.pixel24) {
-        tight_pack24(vs, vs->tight.tight.buffer, w * h, &vs->tight.tight.offset);
+    if (vs->tight->pixel24) {
+        tight_pack24(vs, vs->tight->tight.buffer, w * h,
+                     &vs->tight->tight.offset);
         bytes = 3;
     } else {
         bytes = vs->client_pf.bytes_per_pixel;
     }
 
     bytes = tight_compress_data(vs, stream, w * h * bytes,
-                                tight_conf[vs->tight.compression].raw_zlib_level,
-                                Z_DEFAULT_STRATEGY);
+                            tight_conf[vs->tight->compression].raw_zlib_level,
+                            Z_DEFAULT_STRATEGY);
 
     return (bytes >= 0);
 }
@@ -948,14 +949,14 @@ static int send_solid_rect(VncState *vs)
 
     vnc_write_u8(vs, VNC_TIGHT_FILL << 4); /* no flushing, no filter */
 
-    if (vs->tight.pixel24) {
-        tight_pack24(vs, vs->tight.tight.buffer, 1, &vs->tight.tight.offset);
+    if (vs->tight->pixel24) {
+        tight_pack24(vs, vs->tight->tight.buffer, 1, &vs->tight->tight.offset);
         bytes = 3;
     } else {
         bytes = vs->client_pf.bytes_per_pixel;
     }
 
-    vnc_write(vs, vs->tight.tight.buffer, bytes);
+    vnc_write(vs, vs->tight->tight.buffer, bytes);
     return 1;
 }
 
@@ -964,7 +965,7 @@ static int send_mono_rect(VncState *vs, int x, int y,
 {
     ssize_t bytes;
     int stream = 1;
-    int level = tight_conf[vs->tight.compression].mono_zlib_level;
+    int level = tight_conf[vs->tight->compression].mono_zlib_level;
 
 #ifdef CONFIG_VNC_PNG
     if (tight_can_send_png_rect(vs, w, h)) {
@@ -992,26 +993,26 @@ static int send_mono_rect(VncState *vs, int x, int y,
         uint32_t buf[2] = {bg, fg};
         size_t ret = sizeof (buf);
 
-        if (vs->tight.pixel24) {
+        if (vs->tight->pixel24) {
             tight_pack24(vs, (unsigned char*)buf, 2, &ret);
         }
         vnc_write(vs, buf, ret);
 
-        tight_encode_mono_rect32(vs->tight.tight.buffer, w, h, bg, fg);
+        tight_encode_mono_rect32(vs->tight->tight.buffer, w, h, bg, fg);
         break;
     }
     case 2:
         vnc_write(vs, &bg, 2);
         vnc_write(vs, &fg, 2);
-        tight_encode_mono_rect16(vs->tight.tight.buffer, w, h, bg, fg);
+        tight_encode_mono_rect16(vs->tight->tight.buffer, w, h, bg, fg);
         break;
     default:
         vnc_write_u8(vs, bg);
         vnc_write_u8(vs, fg);
-        tight_encode_mono_rect8(vs->tight.tight.buffer, w, h, bg, fg);
+        tight_encode_mono_rect8(vs->tight->tight.buffer, w, h, bg, fg);
         break;
     }
-    vs->tight.tight.offset = bytes;
+    vs->tight->tight.offset = bytes;
 
     bytes = tight_compress_data(vs, stream, bytes, level, Z_DEFAULT_STRATEGY);
     return (bytes >= 0);
@@ -1041,7 +1042,7 @@ static void write_palette(int idx, uint32_t color, void *opaque)
 static bool send_gradient_rect(VncState *vs, int x, int y, int w, int h)
 {
     int stream = 3;
-    int level = tight_conf[vs->tight.compression].gradient_zlib_level;
+    int level = tight_conf[vs->tight->compression].gradient_zlib_level;
     ssize_t bytes;
 
     if (vs->client_pf.bytes_per_pixel == 1) {
@@ -1051,23 +1052,23 @@ static bool send_gradient_rect(VncState *vs, int x, int y, int w, int h)
     vnc_write_u8(vs, (stream | VNC_TIGHT_EXPLICIT_FILTER) << 4);
     vnc_write_u8(vs, VNC_TIGHT_FILTER_GRADIENT);
 
-    buffer_reserve(&vs->tight.gradient, w * 3 * sizeof (int));
+    buffer_reserve(&vs->tight->gradient, w * 3 * sizeof(int));
 
-    if (vs->tight.pixel24) {
-        tight_filter_gradient24(vs, vs->tight.tight.buffer, w, h);
+    if (vs->tight->pixel24) {
+        tight_filter_gradient24(vs, vs->tight->tight.buffer, w, h);
         bytes = 3;
     } else if (vs->client_pf.bytes_per_pixel == 4) {
-        tight_filter_gradient32(vs, (uint32_t *)vs->tight.tight.buffer, w, h);
+        tight_filter_gradient32(vs, (uint32_t *)vs->tight->tight.buffer, w, h);
         bytes = 4;
     } else {
-        tight_filter_gradient16(vs, (uint16_t *)vs->tight.tight.buffer, w, h);
+        tight_filter_gradient16(vs, (uint16_t *)vs->tight->tight.buffer, w, h);
         bytes = 2;
     }
 
-    buffer_reset(&vs->tight.gradient);
+    buffer_reset(&vs->tight->gradient);
 
     bytes = w * h * bytes;
-    vs->tight.tight.offset = bytes;
+    vs->tight->tight.offset = bytes;
 
     bytes = tight_compress_data(vs, stream, bytes,
                                 level, Z_FILTERED);
@@ -1078,7 +1079,7 @@ static int send_palette_rect(VncState *vs, int x, int y,
                              int w, int h, VncPalette *palette)
 {
     int stream = 2;
-    int level = tight_conf[vs->tight.compression].idx_zlib_level;
+    int level = tight_conf[vs->tight->compression].idx_zlib_level;
     int colors;
     ssize_t bytes;
 
@@ -1105,12 +1106,12 @@ static int send_palette_rect(VncState *vs, int x, int y,
         palette_iter(palette, write_palette, &priv);
         vnc_write(vs, header, sizeof(header));
 
-        if (vs->tight.pixel24) {
+        if (vs->tight->pixel24) {
             tight_pack24(vs, vs->output.buffer + old_offset, colors, &offset);
             vs->output.offset = old_offset + offset;
         }
 
-        tight_encode_indexed_rect32(vs->tight.tight.buffer, w * h, palette);
+        tight_encode_indexed_rect32(vs->tight->tight.buffer, w * h, palette);
         break;
     }
     case 2:
@@ -1120,7 +1121,7 @@ static int send_palette_rect(VncState *vs, int x, int y,
 
         palette_iter(palette, write_palette, &priv);
         vnc_write(vs, header, sizeof(header));
-        tight_encode_indexed_rect16(vs->tight.tight.buffer, w * h, palette);
+        tight_encode_indexed_rect16(vs->tight->tight.buffer, w * h, palette);
         break;
     }
     default:
@@ -1128,7 +1129,7 @@ static int send_palette_rect(VncState *vs, int x, int y,
         break;
     }
     bytes = w * h;
-    vs->tight.tight.offset = bytes;
+    vs->tight->tight.offset = bytes;
 
     bytes = tight_compress_data(vs, stream, bytes,
                                 level, Z_DEFAULT_STRATEGY);
@@ -1147,7 +1148,7 @@ static int send_palette_rect(VncState *vs, int x, int y,
 static void jpeg_init_destination(j_compress_ptr cinfo)
 {
     VncState *vs = cinfo->client_data;
-    Buffer *buffer = &vs->tight.jpeg;
+    Buffer *buffer = &vs->tight->jpeg;
 
     cinfo->dest->next_output_byte = (JOCTET *)buffer->buffer + buffer->offset;
     cinfo->dest->free_in_buffer = (size_t)(buffer->capacity - buffer->offset);
@@ -1157,7 +1158,7 @@ static void jpeg_init_destination(j_compress_ptr cinfo)
 static boolean jpeg_empty_output_buffer(j_compress_ptr cinfo)
 {
     VncState *vs = cinfo->client_data;
-    Buffer *buffer = &vs->tight.jpeg;
+    Buffer *buffer = &vs->tight->jpeg;
 
     buffer->offset = buffer->capacity;
     buffer_reserve(buffer, 2048);
@@ -1169,7 +1170,7 @@ static boolean jpeg_empty_output_buffer(j_compress_ptr cinfo)
 static void jpeg_term_destination(j_compress_ptr cinfo)
 {
     VncState *vs = cinfo->client_data;
-    Buffer *buffer = &vs->tight.jpeg;
+    Buffer *buffer = &vs->tight->jpeg;
 
     buffer->offset = buffer->capacity - cinfo->dest->free_in_buffer;
 }
@@ -1188,7 +1189,7 @@ static int send_jpeg_rect(VncState *vs, int x, int y, int w, int h, int quality)
         return send_full_color_rect(vs, x, y, w, h);
     }
 
-    buffer_reserve(&vs->tight.jpeg, 2048);
+    buffer_reserve(&vs->tight->jpeg, 2048);
 
     cinfo.err = jpeg_std_error(&jerr);
     jpeg_create_compress(&cinfo);
@@ -1223,9 +1224,9 @@ static int send_jpeg_rect(VncState *vs, int x, int y, int w, int h, int quality)
 
     vnc_write_u8(vs, VNC_TIGHT_JPEG << 4);
 
-    tight_send_compact_size(vs, vs->tight.jpeg.offset);
-    vnc_write(vs, vs->tight.jpeg.buffer, vs->tight.jpeg.offset);
-    buffer_reset(&vs->tight.jpeg);
+    tight_send_compact_size(vs, vs->tight->jpeg.offset);
+    vnc_write(vs, vs->tight->jpeg.buffer, vs->tight->jpeg.offset);
+    buffer_reset(&vs->tight->jpeg);
 
     return 1;
 }
@@ -1241,7 +1242,7 @@ static void write_png_palette(int idx, uint32_t pix, void *opaque)
     VncState *vs = priv->vs;
     png_colorp color = &priv->png_palette[idx];
 
-    if (vs->tight.pixel24)
+    if (vs->tight->pixel24)
     {
         color->red = (pix >> vs->client_pf.rshift) & vs->client_pf.rmax;
         color->green = (pix >> vs->client_pf.gshift) & vs->client_pf.gmax;
@@ -1268,10 +1269,10 @@ static void png_write_data(png_structp png_ptr, png_bytep data,
 {
     VncState *vs = png_get_io_ptr(png_ptr);
 
-    buffer_reserve(&vs->tight.png, vs->tight.png.offset + length);
-    memcpy(vs->tight.png.buffer + vs->tight.png.offset, data, length);
+    buffer_reserve(&vs->tight->png, vs->tight->png.offset + length);
+    memcpy(vs->tight->png.buffer + vs->tight->png.offset, data, length);
 
-    vs->tight.png.offset += length;
+    vs->tight->png.offset += length;
 }
 
 static void png_flush_data(png_structp png_ptr)
@@ -1296,8 +1297,8 @@ static int send_png_rect(VncState *vs, int x, int y, int w, int h,
     png_infop info_ptr;
     png_colorp png_palette = NULL;
     pixman_image_t *linebuf;
-    int level = tight_png_conf[vs->tight.compression].png_zlib_level;
-    int filters = tight_png_conf[vs->tight.compression].png_filters;
+    int level = tight_png_conf[vs->tight->compression].png_zlib_level;
+    int filters = tight_png_conf[vs->tight->compression].png_filters;
     uint8_t *buf;
     int dy;
 
@@ -1341,21 +1342,23 @@ static int send_png_rect(VncState *vs, int x, int y, int w, int h,
         png_set_PLTE(png_ptr, info_ptr, png_palette, palette_size(palette));
 
         if (vs->client_pf.bytes_per_pixel == 4) {
-            tight_encode_indexed_rect32(vs->tight.tight.buffer, w * h, palette);
+            tight_encode_indexed_rect32(vs->tight->tight.buffer, w * h,
+                                        palette);
         } else {
-            tight_encode_indexed_rect16(vs->tight.tight.buffer, w * h, palette);
+            tight_encode_indexed_rect16(vs->tight->tight.buffer, w * h,
+                                        palette);
         }
     }
 
     png_write_info(png_ptr, info_ptr);
 
-    buffer_reserve(&vs->tight.png, 2048);
+    buffer_reserve(&vs->tight->png, 2048);
     linebuf = qemu_pixman_linebuf_create(PIXMAN_BE_r8g8b8, w);
     buf = (uint8_t *)pixman_image_get_data(linebuf);
     for (dy = 0; dy < h; dy++)
     {
         if (color_type == PNG_COLOR_TYPE_PALETTE) {
-            memcpy(buf, vs->tight.tight.buffer + (dy * w), w);
+            memcpy(buf, vs->tight->tight.buffer + (dy * w), w);
         } else {
             qemu_pixman_linebuf_fill(linebuf, vs->vd->server, w, x, y + dy);
         }
@@ -1373,27 +1376,27 @@ static int send_png_rect(VncState *vs, int x, int y, int w, int h,
 
     vnc_write_u8(vs, VNC_TIGHT_PNG << 4);
 
-    tight_send_compact_size(vs, vs->tight.png.offset);
-    vnc_write(vs, vs->tight.png.buffer, vs->tight.png.offset);
-    buffer_reset(&vs->tight.png);
+    tight_send_compact_size(vs, vs->tight->png.offset);
+    vnc_write(vs, vs->tight->png.buffer, vs->tight->png.offset);
+    buffer_reset(&vs->tight->png);
     return 1;
 }
 #endif /* CONFIG_VNC_PNG */
 
 static void vnc_tight_start(VncState *vs)
 {
-    buffer_reset(&vs->tight.tight);
+    buffer_reset(&vs->tight->tight);
 
     // make the output buffer be the zlib buffer, so we can compress it later
-    vs->tight.tmp = vs->output;
-    vs->output = vs->tight.tight;
+    vs->tight->tmp = vs->output;
+    vs->output = vs->tight->tight;
 }
 
 static void vnc_tight_stop(VncState *vs)
 {
     // switch back to normal output/zlib buffers
-    vs->tight.tight = vs->output;
-    vs->output = vs->tight.tmp;
+    vs->tight->tight = vs->output;
+    vs->output = vs->tight->tmp;
 }
 
 static int send_sub_rect_nojpeg(VncState *vs, int x, int y, int w, int h,
@@ -1427,9 +1430,9 @@ static int send_sub_rect_jpeg(VncState *vs, int x, int y, int w, int h,
     int ret;
 
     if (colors == 0) {
-        if (force || (tight_jpeg_conf[vs->tight.quality].jpeg_full &&
+        if (force || (tight_jpeg_conf[vs->tight->quality].jpeg_full &&
                       tight_detect_smooth_image(vs, w, h))) {
-            int quality = tight_conf[vs->tight.quality].jpeg_quality;
+            int quality = tight_conf[vs->tight->quality].jpeg_quality;
 
             ret = send_jpeg_rect(vs, x, y, w, h, quality);
         } else {
@@ -1441,9 +1444,9 @@ static int send_sub_rect_jpeg(VncState *vs, int x, int y, int w, int h,
         ret = send_mono_rect(vs, x, y, w, h, bg, fg);
     } else if (colors <= 256) {
         if (force || (colors > 96 &&
-                      tight_jpeg_conf[vs->tight.quality].jpeg_idx &&
+                      tight_jpeg_conf[vs->tight->quality].jpeg_idx &&
                       tight_detect_smooth_image(vs, w, h))) {
-            int quality = tight_conf[vs->tight.quality].jpeg_quality;
+            int quality = tight_conf[vs->tight->quality].jpeg_quality;
 
             ret = send_jpeg_rect(vs, x, y, w, h, quality);
         } else {
@@ -1467,20 +1470,20 @@ static int send_sub_rect(VncState *vs, int x, int y, int w, int h)
     bool allow_jpeg = true;
 #endif
 
-    vnc_framebuffer_update(vs, x, y, w, h, vs->tight.type);
+    vnc_framebuffer_update(vs, x, y, w, h, vs->tight->type);
 
     vnc_tight_start(vs);
     vnc_raw_send_framebuffer_update(vs, x, y, w, h);
     vnc_tight_stop(vs);
 
 #ifdef CONFIG_VNC_JPEG
-    if (!vs->vd->non_adaptive && vs->tight.quality != (uint8_t)-1) {
+    if (!vs->vd->non_adaptive && vs->tight->quality != (uint8_t)-1) {
         double freq = vnc_update_freq(vs, x, y, w, h);
 
-        if (freq < tight_jpeg_conf[vs->tight.quality].jpeg_freq_min) {
+        if (freq < tight_jpeg_conf[vs->tight->quality].jpeg_freq_min) {
             allow_jpeg = false;
         }
-        if (freq >= tight_jpeg_conf[vs->tight.quality].jpeg_freq_threshold) {
+        if (freq >= tight_jpeg_conf[vs->tight->quality].jpeg_freq_threshold) {
             force_jpeg = true;
             vnc_sent_lossy_rect(vs, x, y, w, h);
         }
@@ -1490,7 +1493,7 @@ static int send_sub_rect(VncState *vs, int x, int y, int w, int h)
     colors = tight_fill_palette(vs, x, y, w * h, &fg, &bg, &palette);
 
 #ifdef CONFIG_VNC_JPEG
-    if (allow_jpeg && vs->tight.quality != (uint8_t)-1) {
+    if (allow_jpeg && vs->tight->quality != (uint8_t)-1) {
         ret = send_sub_rect_jpeg(vs, x, y, w, h, bg, fg, colors, palette,
                                  force_jpeg);
     } else {
@@ -1506,7 +1509,7 @@ static int send_sub_rect(VncState *vs, int x, int y, int w, int h)
 
 static int send_sub_rect_solid(VncState *vs, int x, int y, int w, int h)
 {
-    vnc_framebuffer_update(vs, x, y, w, h, vs->tight.type);
+    vnc_framebuffer_update(vs, x, y, w, h, vs->tight->type);
 
     vnc_tight_start(vs);
     vnc_raw_send_framebuffer_update(vs, x, y, w, h);
@@ -1524,8 +1527,8 @@ static int send_rect_simple(VncState *vs, int x, int y, int w, int h,
     int rw, rh;
     int n = 0;
 
-    max_size = tight_conf[vs->tight.compression].max_rect_size;
-    max_width = tight_conf[vs->tight.compression].max_rect_width;
+    max_size = tight_conf[vs->tight->compression].max_rect_size;
+    max_width = tight_conf[vs->tight->compression].max_rect_width;
 
     if (split && (w > max_width || w * h > max_size)) {
         max_sub_width = (w > max_width) ? max_width : w;
@@ -1634,16 +1637,16 @@ static int tight_send_framebuffer_update(VncState *vs, int x, int y,
 
     if (vs->client_pf.bytes_per_pixel == 4 && vs->client_pf.rmax == 0xFF &&
         vs->client_pf.bmax == 0xFF && vs->client_pf.gmax == 0xFF) {
-        vs->tight.pixel24 = true;
+        vs->tight->pixel24 = true;
     } else {
-        vs->tight.pixel24 = false;
+        vs->tight->pixel24 = false;
     }
 
 #ifdef CONFIG_VNC_JPEG
-    if (vs->tight.quality != (uint8_t)-1) {
+    if (vs->tight->quality != (uint8_t)-1) {
         double freq = vnc_update_freq(vs, x, y, w, h);
 
-        if (freq > tight_jpeg_conf[vs->tight.quality].jpeg_freq_threshold) {
+        if (freq > tight_jpeg_conf[vs->tight->quality].jpeg_freq_threshold) {
             return send_rect_simple(vs, x, y, w, h, false);
         }
     }
@@ -1655,8 +1658,8 @@ static int tight_send_framebuffer_update(VncState *vs, int x, int y,
 
     /* Calculate maximum number of rows in one non-solid rectangle. */
 
-    max_rows = tight_conf[vs->tight.compression].max_rect_size;
-    max_rows /= MIN(tight_conf[vs->tight.compression].max_rect_width, w);
+    max_rows = tight_conf[vs->tight->compression].max_rect_size;
+    max_rows /= MIN(tight_conf[vs->tight->compression].max_rect_width, w);
 
     return find_large_solid_color_rect(vs, x, y, w, h, max_rows);
 }
@@ -1664,33 +1667,33 @@ static int tight_send_framebuffer_update(VncState *vs, int x, int y,
 int vnc_tight_send_framebuffer_update(VncState *vs, int x, int y,
                                       int w, int h)
 {
-    vs->tight.type = VNC_ENCODING_TIGHT;
+    vs->tight->type = VNC_ENCODING_TIGHT;
     return tight_send_framebuffer_update(vs, x, y, w, h);
 }
 
 int vnc_tight_png_send_framebuffer_update(VncState *vs, int x, int y,
                                           int w, int h)
 {
-    vs->tight.type = VNC_ENCODING_TIGHT_PNG;
+    vs->tight->type = VNC_ENCODING_TIGHT_PNG;
     return tight_send_framebuffer_update(vs, x, y, w, h);
 }
 
 void vnc_tight_clear(VncState *vs)
 {
     int i;
-    for (i=0; i<ARRAY_SIZE(vs->tight.stream); i++) {
-        if (vs->tight.stream[i].opaque) {
-            deflateEnd(&vs->tight.stream[i]);
+    for (i = 0; i < ARRAY_SIZE(vs->tight->stream); i++) {
+        if (vs->tight->stream[i].opaque) {
+            deflateEnd(&vs->tight->stream[i]);
         }
     }
 
-    buffer_free(&vs->tight.tight);
-    buffer_free(&vs->tight.zlib);
-    buffer_free(&vs->tight.gradient);
+    buffer_free(&vs->tight->tight);
+    buffer_free(&vs->tight->zlib);
+    buffer_free(&vs->tight->gradient);
 #ifdef CONFIG_VNC_JPEG
-    buffer_free(&vs->tight.jpeg);
+    buffer_free(&vs->tight->jpeg);
 #endif
 #ifdef CONFIG_VNC_PNG
-    buffer_free(&vs->tight.png);
+    buffer_free(&vs->tight->png);
 #endif
 }
diff --git a/ui/vnc-enc-zlib.c b/ui/vnc-enc-zlib.c
index d1b97f2516..5c31fe5771 100644
--- a/ui/vnc-enc-zlib.c
+++ b/ui/vnc-enc-zlib.c
@@ -75,7 +75,8 @@ static int vnc_zlib_stop(VncState *vs)
         zstream->zalloc = vnc_zlib_zalloc;
         zstream->zfree = vnc_zlib_zfree;
 
-        err = deflateInit2(zstream, vs->tight.compression, Z_DEFLATED, MAX_WBITS,
+        err = deflateInit2(zstream, vs->tight->compression, Z_DEFLATED,
+                           MAX_WBITS,
                            MAX_MEM_LEVEL, Z_DEFAULT_STRATEGY);
 
         if (err != Z_OK) {
@@ -83,16 +84,16 @@ static int vnc_zlib_stop(VncState *vs)
             return -1;
         }
 
-        vs->zlib.level = vs->tight.compression;
+        vs->zlib.level = vs->tight->compression;
         zstream->opaque = vs;
     }
 
-    if (vs->tight.compression != vs->zlib.level) {
-        if (deflateParams(zstream, vs->tight.compression,
+    if (vs->tight->compression != vs->zlib.level) {
+        if (deflateParams(zstream, vs->tight->compression,
                           Z_DEFAULT_STRATEGY) != Z_OK) {
             return -1;
         }
-        vs->zlib.level = vs->tight.compression;
+        vs->zlib.level = vs->tight->compression;
     }
 
     // reserve memory in output buffer
diff --git a/ui/vnc-enc-zrle-template.c b/ui/vnc-enc-zrle-template.c
index 70ae624ee9..6687f8cb0e 100644
--- a/ui/vnc-enc-zrle-template.c
+++ b/ui/vnc-enc-zrle-template.c
@@ -96,7 +96,7 @@ static void ZRLE_ENCODE(VncState *vs, int x, int y, int w, int h,
 static void ZRLE_ENCODE_TILE(VncState *vs, ZRLE_PIXEL *data, int w, int h,
                              int zywrle_level)
 {
-    VncPalette *palette = &vs->zrle.palette;
+    VncPalette *palette = &vs->zrle->palette;
 
     int runs = 0;
     int single_pixels = 0;
diff --git a/ui/vnc-enc-zrle.c b/ui/vnc-enc-zrle.c
index ed3b48465d..c85758fe2e 100644
--- a/ui/vnc-enc-zrle.c
+++ b/ui/vnc-enc-zrle.c
@@ -36,18 +36,18 @@ static const int bits_per_packed_pixel[] = {
 
 static void vnc_zrle_start(VncState *vs)
 {
-    buffer_reset(&vs->zrle.zrle);
+    buffer_reset(&vs->zrle->zrle);
 
     /* make the output buffer be the zlib buffer, so we can compress it later */
-    vs->zrle.tmp = vs->output;
-    vs->output = vs->zrle.zrle;
+    vs->zrle->tmp = vs->output;
+    vs->output = vs->zrle->zrle;
 }
 
 static void vnc_zrle_stop(VncState *vs)
 {
     /* switch back to normal output/zlib buffers */
-    vs->zrle.zrle = vs->output;
-    vs->output = vs->zrle.tmp;
+    vs->zrle->zrle = vs->output;
+    vs->output = vs->zrle->tmp;
 }
 
 static void *zrle_convert_fb(VncState *vs, int x, int y, int w, int h,
@@ -55,24 +55,24 @@ static void *zrle_convert_fb(VncState *vs, int x, int y, int w, int h,
 {
     Buffer tmp;
 
-    buffer_reset(&vs->zrle.fb);
-    buffer_reserve(&vs->zrle.fb, w * h * bpp + bpp);
+    buffer_reset(&vs->zrle->fb);
+    buffer_reserve(&vs->zrle->fb, w * h * bpp + bpp);
 
     tmp = vs->output;
-    vs->output = vs->zrle.fb;
+    vs->output = vs->zrle->fb;
 
     vnc_raw_send_framebuffer_update(vs, x, y, w, h);
 
-    vs->zrle.fb = vs->output;
+    vs->zrle->fb = vs->output;
     vs->output = tmp;
-    return vs->zrle.fb.buffer;
+    return vs->zrle->fb.buffer;
 }
 
 static int zrle_compress_data(VncState *vs, int level)
 {
-    z_streamp zstream = &vs->zrle.stream;
+    z_streamp zstream = &vs->zrle->stream;
 
-    buffer_reset(&vs->zrle.zlib);
+    buffer_reset(&vs->zrle->zlib);
 
     if (zstream->opaque != vs) {
         int err;
@@ -92,13 +92,13 @@ static int zrle_compress_data(VncState *vs, int level)
     }
 
     /* reserve memory in output buffer */
-    buffer_reserve(&vs->zrle.zlib, vs->zrle.zrle.offset + 64);
+    buffer_reserve(&vs->zrle->zlib, vs->zrle->zrle.offset + 64);
 
     /* set pointers */
-    zstream->next_in = vs->zrle.zrle.buffer;
-    zstream->avail_in = vs->zrle.zrle.offset;
-    zstream->next_out = vs->zrle.zlib.buffer + vs->zrle.zlib.offset;
-    zstream->avail_out = vs->zrle.zlib.capacity - vs->zrle.zlib.offset;
+    zstream->next_in = vs->zrle->zrle.buffer;
+    zstream->avail_in = vs->zrle->zrle.offset;
+    zstream->next_out = vs->zrle->zlib.buffer + vs->zrle->zlib.offset;
+    zstream->avail_out = vs->zrle->zlib.capacity - vs->zrle->zlib.offset;
     zstream->data_type = Z_BINARY;
 
     /* start encoding */
@@ -107,8 +107,8 @@ static int zrle_compress_data(VncState *vs, int level)
         return -1;
     }
 
-    vs->zrle.zlib.offset = vs->zrle.zlib.capacity - zstream->avail_out;
-    return vs->zrle.zlib.offset;
+    vs->zrle->zlib.offset = vs->zrle->zlib.capacity - zstream->avail_out;
+    return vs->zrle->zlib.offset;
 }
 
 /* Try to work out whether to use RLE and/or a palette.  We do this by
@@ -259,14 +259,14 @@ static int zrle_send_framebuffer_update(VncState *vs, int x, int y,
     size_t bytes;
     int zywrle_level;
 
-    if (vs->zrle.type == VNC_ENCODING_ZYWRLE) {
-        if (!vs->vd->lossy || vs->tight.quality == (uint8_t)-1
-            || vs->tight.quality == 9) {
+    if (vs->zrle->type == VNC_ENCODING_ZYWRLE) {
+        if (!vs->vd->lossy || vs->tight->quality == (uint8_t)-1
+            || vs->tight->quality == 9) {
             zywrle_level = 0;
-            vs->zrle.type = VNC_ENCODING_ZRLE;
-        } else if (vs->tight.quality < 3) {
+            vs->zrle->type = VNC_ENCODING_ZRLE;
+        } else if (vs->tight->quality < 3) {
             zywrle_level = 3;
-        } else if (vs->tight.quality < 6) {
+        } else if (vs->tight->quality < 6) {
             zywrle_level = 2;
         } else {
             zywrle_level = 1;
@@ -337,30 +337,30 @@ static int zrle_send_framebuffer_update(VncState *vs, int x, int y,
 
     vnc_zrle_stop(vs);
     bytes = zrle_compress_data(vs, Z_DEFAULT_COMPRESSION);
-    vnc_framebuffer_update(vs, x, y, w, h, vs->zrle.type);
+    vnc_framebuffer_update(vs, x, y, w, h, vs->zrle->type);
     vnc_write_u32(vs, bytes);
-    vnc_write(vs, vs->zrle.zlib.buffer, vs->zrle.zlib.offset);
+    vnc_write(vs, vs->zrle->zlib.buffer, vs->zrle->zlib.offset);
     return 1;
 }
 
 int vnc_zrle_send_framebuffer_update(VncState *vs, int x, int y, int w, int h)
 {
-    vs->zrle.type = VNC_ENCODING_ZRLE;
+    vs->zrle->type = VNC_ENCODING_ZRLE;
     return zrle_send_framebuffer_update(vs, x, y, w, h);
 }
 
 int vnc_zywrle_send_framebuffer_update(VncState *vs, int x, int y, int w, int h)
 {
-    vs->zrle.type = VNC_ENCODING_ZYWRLE;
+    vs->zrle->type = VNC_ENCODING_ZYWRLE;
     return zrle_send_framebuffer_update(vs, x, y, w, h);
 }
 
 void vnc_zrle_clear(VncState *vs)
 {
-    if (vs->zrle.stream.opaque) {
-        deflateEnd(&vs->zrle.stream);
+    if (vs->zrle->stream.opaque) {
+        deflateEnd(&vs->zrle->stream);
     }
-    buffer_free(&vs->zrle.zrle);
-    buffer_free(&vs->zrle.fb);
-    buffer_free(&vs->zrle.zlib);
+    buffer_free(&vs->zrle->zrle);
+    buffer_free(&vs->zrle->fb);
+    buffer_free(&vs->zrle->zlib);
 }
diff --git a/ui/vnc.c b/ui/vnc.c
index 99b1ab14a5..0acdd3870f 100644
--- a/ui/vnc.c
+++ b/ui/vnc.c
@@ -1141,6 +1141,8 @@ void vnc_disconnect_finish(VncState *vs)
         g_free(vs->lossy_rect[i]);
     }
     g_free(vs->lossy_rect);
+    g_free(vs->zrle);
+    g_free(vs->tight);
     g_free(vs);
 }
 
@@ -2003,8 +2005,8 @@ static void set_encodings(VncState *vs, int32_t *encodings, size_t n_encodings)
 
     vs->features = 0;
     vs->vnc_encoding = 0;
-    vs->tight.compression = 9;
-    vs->tight.quality = -1; /* Lossless by default */
+    vs->tight->compression = 9;
+    vs->tight->quality = -1; /* Lossless by default */
     vs->absolute = -1;
 
     /*
@@ -2069,11 +2071,11 @@ static void set_encodings(VncState *vs, int32_t *encodings, size_t n_encodings)
             vs->features |= VNC_FEATURE_LED_STATE_MASK;
             break;
         case VNC_ENCODING_COMPRESSLEVEL0 ... VNC_ENCODING_COMPRESSLEVEL0 + 9:
-            vs->tight.compression = (enc & 0x0F);
+            vs->tight->compression = (enc & 0x0F);
             break;
         case VNC_ENCODING_QUALITYLEVEL0 ... VNC_ENCODING_QUALITYLEVEL0 + 9:
             if (vs->vd->lossy) {
-                vs->tight.quality = (enc & 0x0F);
+                vs->tight->quality = (enc & 0x0F);
             }
             break;
         default:
@@ -2906,6 +2908,8 @@ static void vnc_connect(VncDisplay *vd, int csock, int skipauth, bool websocket)
     int i;
 
     vs->csock = csock;
+    vs->zrle = g_new0(VncZrle, 1);
+    vs->tight = g_new0(VncTight, 1);
 
     if (skipauth) {
 	vs->auth = VNC_AUTH_NONE;
diff --git a/ui/vnc.h b/ui/vnc.h
index f9c5f89950..99af25748a 100644
--- a/ui/vnc.h
+++ b/ui/vnc.h
@@ -346,10 +346,10 @@ struct VncState
     /* Encoding specific, if you add something here, don't forget to
      *  update vnc_async_encoding_start()
      */
-    VncTight tight;
+    VncTight *tight;
     VncZlib zlib;
     VncHextile hextile;
-    VncZrle zrle;
+    VncZrle *zrle;
     VncZywrle zywrle;
 
     Notifier mouse_mode_notifier;
-- 
2.18.2