[PATCH] drm/exynos: dpi: Fix NULL pointer dereference with legacy bindings

[Tomasz Figa <tomasz.figa@gmail.com>]

If there is no panel node in DT and instead display timings are provided
directly in FIMD node, there is no panel object created and ctx->panel
becomes NULL. However during Exynos DRM initialization
drm_helper_hpd_irq_event() is called, which in turns calls
exynos_dpi_detect(), which dereferences ctx->panel without a check,
causing a NULL pointer derefrence.

This patch fixes the issue by adding necessary NULL pointer check.

Signed-off-by: Tomasz Figa <tomasz.figa@gmail.com>
---
 drivers/gpu/drm/exynos/exynos_drm_dpi.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/exynos/exynos_drm_dpi.c b/drivers/gpu/drm/exynos/exynos_drm_dpi.c
index f1b8587..f44bd90 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_dpi.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_dpi.c
@@ -40,7 +40,7 @@ exynos_dpi_detect(struct drm_connector *connector, bool force)
 {
 	struct exynos_dpi *ctx = connector_to_dpi(connector);
 
-	if (!ctx->panel->connector)
+	if (ctx->panel && !ctx->panel->connector)
 		drm_panel_attach(ctx->panel, &ctx->connector);
 
 	return connector_status_connected;
-- 
2.0.0