egl/dri2: NULL check value returned by dri2_create_surface

dri2_create_surface can fail for a variety of reasons, including bad
input data.  Dereferencing the NULL pointer and crashing is not okay.

Fixes issue identified by Klocwork analysis:

    Pointer 'surf' returned from call to function 'dri2_create_surface'
    at line 285 may be NULL and will be dereferenced at line 291.

NOTE: This is a candidate for the stable branches.

Signed-off-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

1 files changed, 9 insertions, 8 deletions

diff --git a/src/egl/drivers/dri2/platform_x11.c b/src/egl/drivers/dri2/platform_x11.c
index e9ca241..ccb097f 100644
--- a/src/egl/drivers/dri2/platform_x11.c
+++ b/src/egl/drivers/dri2/platform_x11.c
@@ -284,14 +284,15 @@ dri2_create_window_surface(_EGLDriver *drv, _EGLDisplay *disp,
 
    surf = dri2_create_surface(drv, disp, EGL_WINDOW_BIT, conf,
                               window, attrib_list);
-
-   /* When we first create the DRI2 drawable, its swap interval on the server
-    * side is 1.
-    */
-   surf->SwapInterval = 1;
-
-   /* Override that with a driconf-set value. */
-   drv->API.SwapInterval(drv, disp, surf, dri2_dpy->default_swap_interval);
+   if (surf != NULL) {
+      /* When we first create the DRI2 drawable, its swap interval on the
+       * server side is 1.
+       */
+      surf->SwapInterval = 1;
+
+      /* Override that with a driconf-set value. */
+      drv->API.SwapInterval(drv, disp, surf, dri2_dpy->default_swap_interval);
+   }
 
    return surf;
 }