drm: fix a use-after-free when GPU acceleration disabled

[pandora-kernel.git] / drivers / gpu / drm / drm_irq.c

diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c
index 44a5d0a..73af885 100644 (file)
--- a/drivers/gpu/drm/drm_irq.c
+++ b/drivers/gpu/drm/drm_irq.c
@@ -981,7 +981,7 @@ EXPORT_SYMBOL(drm_vblank_off);
  */
 void drm_vblank_pre_modeset(struct drm_device *dev, int crtc)
 {
-       /* vblank is not initialized (IRQ not installed ?) */
+       /* vblank is not initialized (IRQ not installed ?), or has been freed */
        if (!dev->num_crtcs)
                return;
        /*
@@ -1003,6 +1003,10 @@ void drm_vblank_post_modeset(struct drm_device *dev, int crtc)
 {
        unsigned long irqflags;
 
+       /* vblank is not initialized (IRQ not installed ?), or has been freed */
+       if (!dev->num_crtcs)
+               return;
+
        if (dev->vblank_inmodeset[crtc]) {
                spin_lock_irqsave(&dev->vbl_lock, irqflags);
                dev->vblank_disable_allowed = 1;