include/ui/console.h | 2 ++ ui/console.c | 10 ++++++---- ui/vnc.c | 10 ++++++++++ 3 files changed, 18 insertions(+), 4 deletions(-)
Secondary displays in multihead setups are allowed to have a NULL
DisplaySurface. Typically user interfaces handle this by hiding the
window which shows the display in question.
This isn't an option for vnc though because it simply hasn't a concept
of windows or outputs. So handle the situation by showing a placeholder
DisplaySurface instead. Also check in console_select whenever a surface
is preset in the first place before requesting an update.
This fixes a segfault which can be triggered by switching to an unused
display (via vtrl-alt-<nr>) in a multihead setup, for example using
-device virtio-vga,max_outputs=2.
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
include/ui/console.h | 2 ++
ui/console.c | 10 ++++++----
ui/vnc.c | 10 ++++++++++
3 files changed, 18 insertions(+), 4 deletions(-)
diff --git a/include/ui/console.h b/include/ui/console.h
index aae9e44cb3..5fca9afcbc 100644
--- a/include/ui/console.h
+++ b/include/ui/console.h
@@ -260,6 +260,8 @@ DisplaySurface *qemu_create_displaysurface_guestmem(int width, int height,
pixman_format_code_t format,
int linesize,
uint64_t addr);
+DisplaySurface *qemu_create_message_surface(int w, int h,
+ const char *msg);
PixelFormat qemu_default_pixelformat(int bpp);
DisplaySurface *qemu_create_displaysurface(int width, int height);
diff --git a/ui/console.c b/ui/console.c
index 6ab4ff3baf..348610dd43 100644
--- a/ui/console.c
+++ b/ui/console.c
@@ -1039,8 +1039,10 @@ void console_select(unsigned int index)
dcl->ops->dpy_gfx_switch(dcl, s->surface);
}
}
- dpy_gfx_update(s, 0, 0, surface_width(s->surface),
- surface_height(s->surface));
+ if (s->surface) {
+ dpy_gfx_update(s, 0, 0, surface_width(s->surface),
+ surface_height(s->surface));
+ }
}
if (ds->have_text) {
dpy_text_resize(s, s->width, s->height);
@@ -1370,8 +1372,8 @@ DisplaySurface *qemu_create_displaysurface_guestmem(int width, int height,
return surface;
}
-static DisplaySurface *qemu_create_message_surface(int w, int h,
- const char *msg)
+DisplaySurface *qemu_create_message_surface(int w, int h,
+ const char *msg)
{
DisplaySurface *surface = qemu_create_displaysurface(w, h);
pixman_color_t bg = color_table_rgb[0][QEMU_COLOR_BLACK];
diff --git a/ui/vnc.c b/ui/vnc.c
index 13c28cabb0..e164eb798c 100644
--- a/ui/vnc.c
+++ b/ui/vnc.c
@@ -746,9 +746,19 @@ static void vnc_update_server_surface(VncDisplay *vd)
static void vnc_dpy_switch(DisplayChangeListener *dcl,
DisplaySurface *surface)
{
+ static const char placeholder_msg[] =
+ "Display output is not active.";
+ static DisplaySurface *placeholder;
VncDisplay *vd = container_of(dcl, VncDisplay, dcl);
VncState *vs;
+ if (surface == NULL) {
+ if (placeholder == NULL) {
+ placeholder = qemu_create_message_surface(640, 480, placeholder_msg);
+ }
+ surface = placeholder;
+ }
+
vnc_abort_display_jobs(vd);
vd->ds = surface;
--
2.9.3
On 03/08/2018 05:18 PM, Gerd Hoffmann wrote: > Secondary displays in multihead setups are allowed to have a NULL > DisplaySurface. Typically user interfaces handle this by hiding the > window which shows the display in question. > > This isn't an option for vnc though because it simply hasn't a concept > of windows or outputs. So handle the situation by showing a placeholder > DisplaySurface instead. Also check in console_select whenever a surface > is preset in the first place before requesting an update. > > This fixes a segfault which can be triggered by switching to an unused > display (via vtrl-alt-<nr>) in a multihead setup, for example using > -device virtio-vga,max_outputs=2. > > Cc: Christian Borntraeger <borntraeger@de.ibm.com> > Signed-off-by: Gerd Hoffmann <kraxel@redhat.com> Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org> > --- > include/ui/console.h | 2 ++ > ui/console.c | 10 ++++++---- > ui/vnc.c | 10 ++++++++++ > 3 files changed, 18 insertions(+), 4 deletions(-) > > diff --git a/include/ui/console.h b/include/ui/console.h > index aae9e44cb3..5fca9afcbc 100644 > --- a/include/ui/console.h > +++ b/include/ui/console.h > @@ -260,6 +260,8 @@ DisplaySurface *qemu_create_displaysurface_guestmem(int width, int height, > pixman_format_code_t format, > int linesize, > uint64_t addr); > +DisplaySurface *qemu_create_message_surface(int w, int h, > + const char *msg); > PixelFormat qemu_default_pixelformat(int bpp); > > DisplaySurface *qemu_create_displaysurface(int width, int height); > diff --git a/ui/console.c b/ui/console.c > index 6ab4ff3baf..348610dd43 100644 > --- a/ui/console.c > +++ b/ui/console.c > @@ -1039,8 +1039,10 @@ void console_select(unsigned int index) > dcl->ops->dpy_gfx_switch(dcl, s->surface); > } > } > - dpy_gfx_update(s, 0, 0, surface_width(s->surface), > - surface_height(s->surface)); > + if (s->surface) { > + dpy_gfx_update(s, 0, 0, surface_width(s->surface), > + surface_height(s->surface)); > + } > } > if (ds->have_text) { > dpy_text_resize(s, s->width, s->height); > @@ -1370,8 +1372,8 @@ DisplaySurface *qemu_create_displaysurface_guestmem(int width, int height, > return surface; > } > > -static DisplaySurface *qemu_create_message_surface(int w, int h, > - const char *msg) > +DisplaySurface *qemu_create_message_surface(int w, int h, > + const char *msg) > { > DisplaySurface *surface = qemu_create_displaysurface(w, h); > pixman_color_t bg = color_table_rgb[0][QEMU_COLOR_BLACK]; > diff --git a/ui/vnc.c b/ui/vnc.c > index 13c28cabb0..e164eb798c 100644 > --- a/ui/vnc.c > +++ b/ui/vnc.c > @@ -746,9 +746,19 @@ static void vnc_update_server_surface(VncDisplay *vd) > static void vnc_dpy_switch(DisplayChangeListener *dcl, > DisplaySurface *surface) > { > + static const char placeholder_msg[] = > + "Display output is not active."; > + static DisplaySurface *placeholder; > VncDisplay *vd = container_of(dcl, VncDisplay, dcl); > VncState *vs; > > + if (surface == NULL) { > + if (placeholder == NULL) { > + placeholder = qemu_create_message_surface(640, 480, placeholder_msg); > + } > + surface = placeholder; > + } > + > vnc_abort_display_jobs(vd); > vd->ds = surface; > >
On 03/08/2018 05:18 PM, Gerd Hoffmann wrote: > Secondary displays in multihead setups are allowed to have a NULL > DisplaySurface. Typically user interfaces handle this by hiding the > window which shows the display in question. > > This isn't an option for vnc though because it simply hasn't a concept > of windows or outputs. So handle the situation by showing a placeholder > DisplaySurface instead. Also check in console_select whenever a surface > is preset in the first place before requesting an update. > > This fixes a segfault which can be triggered by switching to an unused > display (via vtrl-alt-<nr>) in a multihead setup, for example using > -device virtio-vga,max_outputs=2. > > Cc: Christian Borntraeger <borntraeger@de.ibm.com> > Signed-off-by: Gerd Hoffmann <kraxel@redhat.com> > --- Tested-by: Christian Borntraeger <borntraeger@de.ibm.com> I can see the new placeholder message and the crash is gone. > include/ui/console.h | 2 ++ > ui/console.c | 10 ++++++---- > ui/vnc.c | 10 ++++++++++ > 3 files changed, 18 insertions(+), 4 deletions(-) > > diff --git a/include/ui/console.h b/include/ui/console.h > index aae9e44cb3..5fca9afcbc 100644 > --- a/include/ui/console.h > +++ b/include/ui/console.h > @@ -260,6 +260,8 @@ DisplaySurface *qemu_create_displaysurface_guestmem(int width, int height, > pixman_format_code_t format, > int linesize, > uint64_t addr); > +DisplaySurface *qemu_create_message_surface(int w, int h, > + const char *msg); > PixelFormat qemu_default_pixelformat(int bpp); > > DisplaySurface *qemu_create_displaysurface(int width, int height); > diff --git a/ui/console.c b/ui/console.c > index 6ab4ff3baf..348610dd43 100644 > --- a/ui/console.c > +++ b/ui/console.c > @@ -1039,8 +1039,10 @@ void console_select(unsigned int index) > dcl->ops->dpy_gfx_switch(dcl, s->surface); > } > } > - dpy_gfx_update(s, 0, 0, surface_width(s->surface), > - surface_height(s->surface)); > + if (s->surface) { > + dpy_gfx_update(s, 0, 0, surface_width(s->surface), > + surface_height(s->surface)); > + } > } > if (ds->have_text) { > dpy_text_resize(s, s->width, s->height); > @@ -1370,8 +1372,8 @@ DisplaySurface *qemu_create_displaysurface_guestmem(int width, int height, > return surface; > } > > -static DisplaySurface *qemu_create_message_surface(int w, int h, > - const char *msg) > +DisplaySurface *qemu_create_message_surface(int w, int h, > + const char *msg) > { > DisplaySurface *surface = qemu_create_displaysurface(w, h); > pixman_color_t bg = color_table_rgb[0][QEMU_COLOR_BLACK]; > diff --git a/ui/vnc.c b/ui/vnc.c > index 13c28cabb0..e164eb798c 100644 > --- a/ui/vnc.c > +++ b/ui/vnc.c > @@ -746,9 +746,19 @@ static void vnc_update_server_surface(VncDisplay *vd) > static void vnc_dpy_switch(DisplayChangeListener *dcl, > DisplaySurface *surface) > { > + static const char placeholder_msg[] = > + "Display output is not active."; > + static DisplaySurface *placeholder; > VncDisplay *vd = container_of(dcl, VncDisplay, dcl); > VncState *vs; > > + if (surface == NULL) { > + if (placeholder == NULL) { > + placeholder = qemu_create_message_surface(640, 480, placeholder_msg); > + } > + surface = placeholder; > + } > + > vnc_abort_display_jobs(vd); > vd->ds = surface; >
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