ui/console: Precautionary glBindTexture and surface->texture validation in surface_gl_update_texture

In a GVT-g setup with dmabuf and GTK GUI, the current 2D texture at
surface_gl_update_texture is not necessarily
surface->texture. Adding a glBindTexture fixes related crashes and
artifacts, and is generally more secure.

Signed-off-by: HOU Qiming <hqm03ster@gmail.com>
Tested-by: Marcel Apfelbaum<marcel.apfelbaum@gmail.com>
Signed-off-by: Marcel Apfelbaum <marcel.apfelbaum@gmail.com>
Message-id: 20190507080501.26712-1-marcel.apfelbaum@gmail.com
[fixed malformed patch, rebase to master]
Signed-off-by: Marcel Apfelbaum <marcel.apfelbaum@gmail.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

ui/console-gl.c

@@ -92,13 +92,17 @@ void surface_gl_update_texture(QemuGLShader *gls,
 
     assert(gls);
 
-    glPixelStorei(GL_UNPACK_ROW_LENGTH_EXT,
-                  surface_stride(surface) / surface_bytes_per_pixel(surface));
-    glTexSubImage2D(GL_TEXTURE_2D, 0,
-                    x, y, w, h,
-                    surface->glformat, surface->gltype,
-                    data + surface_stride(surface) * y
-                    + surface_bytes_per_pixel(surface) * x);
+    if (surface->texture) {
+        glBindTexture(GL_TEXTURE_2D, surface->texture);
+        glPixelStorei(GL_UNPACK_ROW_LENGTH_EXT,
+                      surface_stride(surface)
+                      / surface_bytes_per_pixel(surface));
+        glTexSubImage2D(GL_TEXTURE_2D, 0,
+                        x, y, w, h,
+                        surface->glformat, surface->gltype,
+                        data + surface_stride(surface) * y
+                        + surface_bytes_per_pixel(surface) * x);
+    }
 }
 
 void surface_gl_render_texture(QemuGLShader *gls,