[PATCH] drm/gud: validate GUD_ROTATION_0 is present in supported rotations

[Sajal Gupta]

The rotation argument to drm_plane_create_rotation_property() is set to
DRM_MODE_ROTATE_0, and the device reported rotation bitmask is used as
the supported_rotations argument. The driver never validates that
GUD_ROTATION_0 is present, so a device that omits it from its
GUD_PROPERTY_ROTATION triggers the
WARN_ON(rotation & ~supported_rotations) in
drm_plane_create_rotation_property()

Fix this by skipping the creation of rotation property if the device
doesn't have the GUD_ROTATION_0 bit

Fixes: 40e1a70b4aed ("drm: Add GUD USB Display driver")
Reported-by: syzbot+efe2810681f1b065d3a8@xxxxxxxxxxxxxxxxxxxxxxxxx
Closes: https://syzkaller.appspot.com/bug?extid=efe2810681f1b065d3a8
Tested-by: syzbot+efe2810681f1b065d3a8@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Sajal Gupta <sajal2005gupta@xxxxxxxxx>
---
 drivers/gpu/drm/gud/gud_drv.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/gud/gud_drv.c b/drivers/gpu/drm/gud/gud_drv.c
index 89bd6ca36003..3a1b9e2a2eaa 100644
--- a/drivers/gpu/drm/gud/gud_drv.c
+++ b/drivers/gpu/drm/gud/gud_drv.c
@@ -289,6 +289,8 @@ static int gud_plane_add_properties(struct gud_device *gdrm)
 			 * but mask out any additions on future devices.
 			 */
 			val &= GUD_ROTATION_MASK;
+			if (!(val & GUD_ROTATION_0))
+				continue;
 			ret = drm_plane_create_rotation_property(&gdrm->plane,
 								 DRM_MODE_ROTATE_0, val);
 			break;
--
2.55.0