From: Daniel Vetter <daniel.vetter@ffwll.ch>
Date: Sat, 20 Aug 2016 10:22:11 +0000 (+0200)
Subject: drm: Reject page_flip for !DRIVER_MODESET
X-Git-Tag: v3.16.39~140
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=3e16efd8ca24a1c0e908feb2e8725a1cb5c87b35;p=thirdparty%2Fkernel%2Fstable.git

drm: Reject page_flip for !DRIVER_MODESET

commit 6f00975c619064a18c23fd3aced325ae165a73b9 upstream.

Somehow this one slipped through, which means drivers without modeset
support can be oopsed (since those also don't call
drm_mode_config_init, which means the crtc lookup will chase an
uninitalized idr).

Reported-by: Alexander Potapenko <glider@google.com>
Cc: Alexander Potapenko <glider@google.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---

diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
index 0dd2c26c55ab8..8cbc8ea28e0e1 100644
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -4236,6 +4236,9 @@ int drm_mode_page_flip_ioctl(struct drm_device *dev,
 	unsigned long flags;
 	int ret = -EINVAL;
 
+	if (!drm_core_check_feature(dev, DRIVER_MODESET))
+		return -EINVAL;
+
 	if (page_flip->flags & ~DRM_MODE_PAGE_FLIP_FLAGS ||
 	    page_flip->reserved != 0)
 		return -EINVAL;