From: Tomi Valkeinen <tomi.valkeinen@ti.com>
Date: Wed, 2 May 2018 12:11:57 +0300
Subject: drm/omap: handle error if scale coefs are not found
Git-commit: e1cdab6e5f9a52e0bdf34363ec0fdab0e2328ba9
Patch-mainline: v4.17-rc5
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166

If get_scale_coef functions fail, they return NULL, but we never check
the return value and could do a NULL deref. This should not happen as we
ought to validate the amount of scaling already earlier, but to be safe,
add the necessary check.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180502091159.7071-3-tomi.valkeinen@ti.com
Reviewed-by: Benoit Parrot <bparrot@ti.com>
Reviewed-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/gpu/drm/omapdrm/dss/dispc.c |    6 ++++++
 1 file changed, 6 insertions(+)

--- a/drivers/gpu/drm/omapdrm/dss/dispc.c
+++ b/drivers/gpu/drm/omapdrm/dss/dispc.c
@@ -828,6 +828,12 @@ static void dispc_ovl_set_scale_coef(str
 	h_coef = dispc_ovl_get_scale_coef(fir_hinc, true);
 	v_coef = dispc_ovl_get_scale_coef(fir_vinc, five_taps);
 
+	if (!h_coef || !v_coef) {
+		dev_err(&dispc->pdev->dev, "%s: failed to find scale coefs\n",
+			__func__);
+		return;
+	}
+
 	for (i = 0; i < 8; i++) {
 		u32 h, hv;