[PATCH 4.19 38/49] drm/nouveau/dp: check for NULL nv_connector->native_mode

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

From: Natalia Petrova <n.petrova@fintech.ru>

[ Upstream commit 20a2ce87fbaf81e4c3dcb631d738e423959eb320 ]

Add checking for NULL before calling nouveau_connector_detect_depth() in
nouveau_connector_get_modes() function because nv_connector->native_mode
could be dereferenced there since connector pointer passed to
nouveau_connector_detect_depth() and the same value of
nv_connector->native_mode is used there.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: d4c2c99bdc83 ("drm/nouveau/dp: remove broken display depth function, use the improved one")

Signed-off-by: Natalia Petrova <n.petrova@fintech.ru>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: Lyude Paul <lyude@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230512111526.82408-1-n.petrova@fintech.ru
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/gpu/drm/nouveau/nouveau_connector.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_connector.c b/drivers/gpu/drm/nouveau/nouveau_connector.c
index b71afde8f115a..0327456913e11 100644
--- a/drivers/gpu/drm/nouveau/nouveau_connector.c
+++ b/drivers/gpu/drm/nouveau/nouveau_connector.c
@@ -916,7 +916,7 @@ nouveau_connector_get_modes(struct drm_connector *connector)
 	/* Determine display colour depth for everything except LVDS now,
 	 * DP requires this before mode_valid() is called.
 	 */
-	if (connector->connector_type != DRM_MODE_CONNECTOR_LVDS)
+	if (connector->connector_type != DRM_MODE_CONNECTOR_LVDS && nv_connector->native_mode)
 		nouveau_connector_detect_depth(connector);
 
 	/* Find the native mode if this is a digital panel, if we didn't
@@ -937,7 +937,7 @@ nouveau_connector_get_modes(struct drm_connector *connector)
 	 * "native" mode as some VBIOS tables require us to use the
 	 * pixel clock as part of the lookup...
 	 */
-	if (connector->connector_type == DRM_MODE_CONNECTOR_LVDS)
+	if (connector->connector_type == DRM_MODE_CONNECTOR_LVDS && nv_connector->native_mode)
 		nouveau_connector_detect_depth(connector);
 
 	if (nv_encoder->dcb->type == DCB_OUTPUT_TV)
-- 
2.39.2