egl: extra null checks for get_xcb_screen() return values

verify get_xcb_screen() returned pointer before using it.

Signed-off-by: Juha-Pekka Heikkila <juhapekka.heikkila@gmail.com>
Reviewed-by: Anuj Phogat <anuj.phogat@gmail.com>

1 files changed, 24 insertions, 6 deletions

diff --git a/src/egl/drivers/dri2/platform_x11.c b/src/egl/drivers/dri2/platform_x11.c
index a7a7338..316ac18 100644
--- a/src/egl/drivers/dri2/platform_x11.c
+++ b/src/egl/drivers/dri2/platform_x11.c
@@ -205,6 +205,7 @@ dri2_x11_create_surface(_EGLDriver *drv, _EGLDisplay *disp, EGLint type,
    xcb_screen_iterator_t s;
    xcb_generic_error_t *error;
    xcb_drawable_t drawable;
+   xcb_screen_t *screen;
 
    STATIC_ASSERT(sizeof(uintptr_t) == sizeof(native_surface));
    drawable = (uintptr_t) native_surface;
@@ -222,11 +223,16 @@ dri2_x11_create_surface(_EGLDriver *drv, _EGLDisplay *disp, EGLint type,
 
    dri2_surf->region = XCB_NONE;
    if (type == EGL_PBUFFER_BIT) {
+      screen = get_xcb_screen(s, dri2_dpy->screen);
+      if (!screen) {
+         _eglError(EGL_BAD_NATIVE_WINDOW, "dri2_create_surface");
+         goto cleanup_surf;
+      }
+
       dri2_surf->drawable = xcb_generate_id(dri2_dpy->conn);
       s = xcb_setup_roots_iterator(xcb_get_setup(dri2_dpy->conn));
       xcb_create_pixmap(dri2_dpy->conn, conf->BufferSize,
-                        dri2_surf->drawable,
-                        get_xcb_screen(s, dri2_dpy->screen)->root,
+                       dri2_surf->drawable, screen->root,
 			dri2_surf->base.Width, dri2_surf->base.Height);
    } else {
       dri2_surf->drawable = drawable;
@@ -504,6 +510,7 @@ dri2_x11_connect(struct dri2_egl_display *dri2_dpy)
    xcb_dri2_connect_cookie_t connect_cookie;
    xcb_generic_error_t *error;
    xcb_screen_iterator_t s;
+   xcb_screen_t *screen;
    char *driver_name, *device_name;
    const xcb_query_extension_reply_t *extension;
 
@@ -527,8 +534,12 @@ dri2_x11_connect(struct dri2_egl_display *dri2_dpy)
 					       XCB_DRI2_MINOR_VERSION);
 
    s = xcb_setup_roots_iterator(xcb_get_setup(dri2_dpy->conn));
-   connect_cookie = xcb_dri2_connect_unchecked(dri2_dpy->conn,
-                                   get_xcb_screen(s, dri2_dpy->screen)->root,
+   screen = get_xcb_screen(s, dri2_dpy->screen);
+   if (!screen) {
+      _eglError(EGL_BAD_NATIVE_WINDOW, "dri2_x11_connect");
+      return EGL_FALSE;
+   }
+   connect_cookie = xcb_dri2_connect_unchecked(dri2_dpy->conn, screen->root,
                                    XCB_DRI2_DRIVER_TYPE_DRI);
 
    xfixes_query =
@@ -589,12 +600,19 @@ dri2_x11_authenticate(_EGLDisplay *disp, uint32_t id)
    xcb_dri2_authenticate_reply_t *authenticate;
    xcb_dri2_authenticate_cookie_t authenticate_cookie;
    xcb_screen_iterator_t s;
+   xcb_screen_t *screen;
    int ret = 0;
 
    s = xcb_setup_roots_iterator(xcb_get_setup(dri2_dpy->conn));
+
+   screen = get_xcb_screen(s, dri2_dpy->screen);
+   if (!screen) {
+      _eglError(EGL_BAD_NATIVE_WINDOW, "dri2_x11_authenticate");
+      return -1;
+   }
+
    authenticate_cookie =
-      xcb_dri2_authenticate_unchecked(dri2_dpy->conn,
-                           get_xcb_screen(s, dri2_dpy->screen)->root, id);
+      xcb_dri2_authenticate_unchecked(dri2_dpy->conn, screen->root, id);
    authenticate =
       xcb_dri2_authenticate_reply(dri2_dpy->conn, authenticate_cookie, NULL);