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cirrus/vnc: zap bitblit support from console code.

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There is a special code path (dpy_gfx_copy) to allow graphic emulation
notify user interface code about bitblit operations carryed out by
guests.  It is supported by cirrus and vnc server.  The intended purpose
is to optimize display scrolls and just send over the scroll op instead
of a full display update.

This is rarely used these days though because modern guests simply don't
use the cirrus blitter any more.  Any linux guest using the cirrus drm
driver doesn't.  Any windows guest newer than winxp doesn't ship with a
cirrus driver any more and thus uses the cirrus as simple framebuffer.

So this code tends to bitrot and bugs can go unnoticed for a long time.
See for example commit "3e10c3e vnc: fix qemu crash because of SIGSEGV"
which fixes a bug lingering in the code for almost a year, added by
commit "c7628bf vnc: only alloc server surface with clients connected".

Also the vnc server will throttle the frame rate in case it figures the
network can't keep up (send buffers are full).  This doesn't work with
dpy_gfx_copy, for any copy operation sent to the vnc client we have to
send all outstanding updates beforehand, otherwise the vnc client might
run the client side blit on outdated data and thereby corrupt the
display.  So this dpy_gfx_copy "optimization" might even make things
worse on slow network links.

Lets kill it once for all.

Oh, and one more reason: Turns out (after writing the patch) we have a
security bug in that code path ...

Fixes: CVE-2016-9603
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Message-id: 1489494419-14340-1-git-send-email-kraxel@redhat.com
This commit is contained in:
Gerd Hoffmann 2017-03-14 13:26:59 +01:00
parent 215902d7b6
commit 50628d3479
4 changed files with 3 additions and 144 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
hw/display/cirrus_vga.c
View File

@ -796,21 +796,15 @@ static int cirrus_do_copy(CirrusVGAState *s, int dst, int src, int w, int h)
}
}
/* we have to flush all pending changes so that the copy
is generated at the appropriate moment in time */
if (notify)
graphic_hw_update(s->vga.con);
(*s->cirrus_rop) (s, s->vga.vram_ptr + s->cirrus_blt_dstaddr,
s->vga.vram_ptr + s->cirrus_blt_srcaddr,
s->cirrus_blt_dstpitch, s->cirrus_blt_srcpitch,
s->cirrus_blt_width, s->cirrus_blt_height);
if (notify) {
qemu_console_copy(s->vga.con,
sx, sy, dx, dy,
s->cirrus_blt_width / depth,
s->cirrus_blt_height);
dpy_gfx_update(s->vga.con, dx, dy,
s->cirrus_blt_width / depth,
s->cirrus_blt_height);
}
/* we don't have to notify the display that this portion has

7
include/ui/console.h
View File

@ -189,9 +189,6 @@ typedef struct DisplayChangeListenerOps {
int x, int y, int w, int h);
void (*dpy_gfx_switch)(DisplayChangeListener *dcl,
struct DisplaySurface *new_surface);
void (*dpy_gfx_copy)(DisplayChangeListener *dcl,
int src_x, int src_y,
int dst_x, int dst_y, int w, int h);
bool (*dpy_gfx_check_format)(DisplayChangeListener *dcl,
pixman_format_code_t format);
@ -277,8 +274,6 @@ int dpy_set_ui_info(QemuConsole *con, QemuUIInfo *info);
void dpy_gfx_update(QemuConsole *con, int x, int y, int w, int h);
void dpy_gfx_replace_surface(QemuConsole *con,
DisplaySurface *surface);
void dpy_gfx_copy(QemuConsole *con, int src_x, int src_y,
int dst_x, int dst_y, int w, int h);
void dpy_text_cursor(QemuConsole *con, int x, int y);
void dpy_text_update(QemuConsole *con, int x, int y, int w, int h);
void dpy_text_resize(QemuConsole *con, int w, int h);
@ -411,8 +406,6 @@ void qemu_console_set_window_id(QemuConsole *con, int window_id);
void console_select(unsigned int index);
void qemu_console_resize(QemuConsole *con, int width, int height);
void qemu_console_copy(QemuConsole *con, int src_x, int src_y,
int dst_x, int dst_y, int w, int h);
DisplaySurface *qemu_console_surface(QemuConsole *con);
/* console-gl.c */

28
ui/console.c
View File

@ -1586,27 +1586,6 @@ static void dpy_refresh(DisplayState *s)
}
}
void dpy_gfx_copy(QemuConsole *con, int src_x, int src_y,
int dst_x, int dst_y, int w, int h)
{
DisplayState *s = con->ds;
DisplayChangeListener *dcl;
if (!qemu_console_is_visible(con)) {
return;
}
QLIST_FOREACH(dcl, &s->listeners, next) {
if (con != (dcl->con ? dcl->con : active_console)) {
continue;
}
if (dcl->ops->dpy_gfx_copy) {
dcl->ops->dpy_gfx_copy(dcl, src_x, src_y, dst_x, dst_y, w, h);
} else { /* TODO */
dcl->ops->dpy_gfx_update(dcl, dst_x, dst_y, w, h);
}
}
}
void dpy_text_cursor(QemuConsole *con, int x, int y)
{
DisplayState *s = con->ds;
@ -2138,13 +2117,6 @@ void qemu_console_resize(QemuConsole *s, int width, int height)
dpy_gfx_replace_surface(s, surface);
}
void qemu_console_copy(QemuConsole *con, int src_x, int src_y,
int dst_x, int dst_y, int w, int h)
{
assert(con->console_type == GRAPHIC_CONSOLE);
dpy_gfx_copy(con, src_x, src_y, dst_x, dst_y, w, h);
}
DisplaySurface *qemu_console_surface(QemuConsole *console)
{
return console->surface;

100
ui/vnc.c
View File

@ -894,105 +894,6 @@ int vnc_send_framebuffer_update(VncState *vs, int x, int y, int w, int h)
return n;
}
static void vnc_copy(VncState *vs, int src_x, int src_y, int dst_x, int dst_y, int w, int h)
{
/* send bitblit op to the vnc client */
vnc_lock_output(vs);
vnc_write_u8(vs, VNC_MSG_SERVER_FRAMEBUFFER_UPDATE);
vnc_write_u8(vs, 0);
vnc_write_u16(vs, 1); /* number of rects */
vnc_framebuffer_update(vs, dst_x, dst_y, w, h, VNC_ENCODING_COPYRECT);
vnc_write_u16(vs, src_x);
vnc_write_u16(vs, src_y);
vnc_unlock_output(vs);
vnc_flush(vs);
}
static void vnc_dpy_copy(DisplayChangeListener *dcl,
int src_x, int src_y,
int dst_x, int dst_y, int w, int h)
{
VncDisplay *vd = container_of(dcl, VncDisplay, dcl);
VncState *vs, *vn;
uint8_t *src_row;
uint8_t *dst_row;
int i, x, y, pitch, inc, w_lim, s;
int cmp_bytes;
if (!vd->server) {
/* no client connected */
return;
}
vnc_refresh_server_surface(vd);
QTAILQ_FOREACH_SAFE(vs, &vd->clients, next, vn) {
if (vnc_has_feature(vs, VNC_FEATURE_COPYRECT)) {
vs->force_update = 1;
vnc_update_client(vs, 1, true);
/* vs might be free()ed here */
}
}
if (!vd->server) {
/* no client connected */
return;
}
/* do bitblit op on the local surface too */
pitch = vnc_server_fb_stride(vd);
src_row = vnc_server_fb_ptr(vd, src_x, src_y);
dst_row = vnc_server_fb_ptr(vd, dst_x, dst_y);
y = dst_y;
inc = 1;
if (dst_y > src_y) {
/* copy backwards */
src_row += pitch * (h-1);
dst_row += pitch * (h-1);
pitch = -pitch;
y = dst_y + h - 1;
inc = -1;
}
w_lim = w - (VNC_DIRTY_PIXELS_PER_BIT - (dst_x % VNC_DIRTY_PIXELS_PER_BIT));
if (w_lim < 0) {
w_lim = w;
} else {
w_lim = w - (w_lim % VNC_DIRTY_PIXELS_PER_BIT);
}
for (i = 0; i < h; i++) {
for (x = 0; x <= w_lim;
x += s, src_row += cmp_bytes, dst_row += cmp_bytes) {
if (x == w_lim) {
if ((s = w - w_lim) == 0)
break;
} else if (!x) {
s = (VNC_DIRTY_PIXELS_PER_BIT -
(dst_x % VNC_DIRTY_PIXELS_PER_BIT));
s = MIN(s, w_lim);
} else {
s = VNC_DIRTY_PIXELS_PER_BIT;
}
cmp_bytes = s * VNC_SERVER_FB_BYTES;
if (memcmp(src_row, dst_row, cmp_bytes) == 0)
continue;
memmove(dst_row, src_row, cmp_bytes);
QTAILQ_FOREACH(vs, &vd->clients, next) {
if (!vnc_has_feature(vs, VNC_FEATURE_COPYRECT)) {
set_bit(((x + dst_x) / VNC_DIRTY_PIXELS_PER_BIT),
vs->dirty[y]);
}
}
}
src_row += pitch - w * VNC_SERVER_FB_BYTES;
dst_row += pitch - w * VNC_SERVER_FB_BYTES;
y += inc;
}
QTAILQ_FOREACH(vs, &vd->clients, next) {
if (vnc_has_feature(vs, VNC_FEATURE_COPYRECT)) {
vnc_copy(vs, src_x, src_y, dst_x, dst_y, w, h);
}
}
}
static void vnc_mouse_set(DisplayChangeListener *dcl,
int x, int y, int visible)
{
@ -3120,7 +3021,6 @@ static gboolean vnc_listen_io(QIOChannel *ioc,
static const DisplayChangeListenerOps dcl_ops = {
.dpy_name = "vnc",
.dpy_refresh = vnc_refresh,
.dpy_gfx_copy = vnc_dpy_copy,
.dpy_gfx_update = vnc_dpy_update,
.dpy_gfx_switch = vnc_dpy_switch,
.dpy_gfx_check_format = qemu_pixman_check_format,