[PATCH] drm: Make sure that encoder_type for drm_encoder_init() is in the list

[Jordan Crouse]

If a encoder name isn't specified for drm_encoder_init() it will try
to construct one based on the incoming encoder_type identifier. If the
caller passes an invalid encoder_type value the lookup could walk right
past the end of the table.

[v2: Use a WARN() at the top of the function as suggested by Daniel
 Vetter]

Signed-off-by: Jordan Crouse <jcrouse at codeaurora.org>
---
 drivers/gpu/drm/drm_encoder.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/drm_encoder.c b/drivers/gpu/drm/drm_encoder.c
index 273e1c59c54a..6228c2cee5f0 100644
--- a/drivers/gpu/drm/drm_encoder.c
+++ b/drivers/gpu/drm/drm_encoder.c
@@ -114,6 +114,10 @@ int drm_encoder_init(struct drm_device *dev,
 	if (WARN_ON(dev->mode_config.num_encoder >= 32))
 		return -EINVAL;
 
+	/* Make sure that the requested encoder type is in the list */
+	if (WARN_ON(encoder_type >= ARRAY_SIZE(drm_encoder_enum_list)))
+		return -EINVAL;
+
 	ret = drm_mode_object_add(dev, &encoder->base, DRM_MODE_OBJECT_ENCODER);
 	if (ret)
 		return ret;
-- 
2.17.1