[PATCH] ui/gtk: Negative Page number is not valid

[dongwon.kim@intel.com]

From: Dongwon Kim <dongwon.kim@intel.com>

Negative page number means the page with that number does not
belong to the notebook so it shouldn't be used as a valid page
number in gd_vc_find_by_page. This function should just return
null in such case.

This change, however, will cause a segfault during detaching
/untabifying process in gtk_release_modifiers because the
current VC's page number suddenly becomes '-1' as soon as
the VC is detached, which makes gd_vc_find_by_page return
null. So gtk_release_modifiers should do the null check on
VC returned from gd_vc_find_by_page.

Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Vivek Kasireddy <vivek.kasireddy@intel.com>
Signed-off-by: Dongwon Kim <dongwon.kim@intel.com>
---
 ui/gtk.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/ui/gtk.c b/ui/gtk.c
index 93b13b7a30..1f8523fd81 100644
--- a/ui/gtk.c
+++ b/ui/gtk.c
@@ -164,7 +164,7 @@ static VirtualConsole *gd_vc_find_by_page(GtkDisplayState *s, gint page)
     for (i = 0; i < s->nb_vcs; i++) {
         vc = &s->vc[i];
         p = gtk_notebook_page_num(GTK_NOTEBOOK(s->notebook), vc->tab_item);
-        if (p == page) {
+        if (p > -1 && p == page) {
             return vc;
         }
     }
@@ -357,7 +357,7 @@ static void gtk_release_modifiers(GtkDisplayState *s)
 {
     VirtualConsole *vc = gd_vc_find_current(s);
 
-    if (vc->type != GD_VC_GFX ||
+    if (!vc || vc->type != GD_VC_GFX ||
         !qemu_console_is_graphic(vc->gfx.dcl.con)) {
         return;
     }
-- 
2.34.1