linux-kernel - [PATCH 3.2 079/152] drm: Reject page_flip for !DRIVER

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Message-ID: <lsq.1479082447.158872804@decadent.org.uk>
Date:   Mon, 14 Nov 2016 00:14:07 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org,
        "Chris Wilson" <chris@...is-wilson.co.uk>,
        "Alexander Potapenko" <glider@...gle.com>,
        "Daniel Vetter" <daniel.vetter@...ll.ch>,
        "Dave Airlie" <airlied@...hat.com>,
        "Daniel Vetter" <daniel.vetter@...el.com>
Subject: [PATCH 3.2 079/152] drm: Reject page_flip for !DRIVER_MODESET

3.2.84-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Daniel Vetter <daniel.vetter@...ll.ch>

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@...gle.com>
Cc: Alexander Potapenko <glider@...gle.com>
Signed-off-by: Daniel Vetter <daniel.vetter@...el.com>
Reviewed-by: Chris Wilson <chris@...is-wilson.co.uk>
Signed-off-by: Dave Airlie <airlied@...hat.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/gpu/drm/drm_crtc.c | 3 +++
 1 file changed, 3 insertions(+)

--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -2675,6 +2675,9 @@ int drm_mode_page_flip_ioctl(struct drm_
 	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;