[PATCH v3 2/2] drm/sun4i: tcon: prevent tcon->panel dereference if NULL

From: Giulio Benetti
Date: Fri Oct 05 2018 - 18:00:02 EST


If tcon->panel pointer is NULL, trying to dereference from it
(i.e. tcon->panel->connector) will cause a null pointer dereference.

Add tcon->panel null pointer check before calling
sun4i_tcon0_mode_set_dithering().

Signed-off-by: Giulio Benetti <giulio.benetti@xxxxxxxxxxxxxxxx>
Fixes: f11adcecbd5f ("drm/sun4i: tcon: Add dithering support for
RGB565/RGB666 LCD panels")
Reviewed-by: Chen-Yu Tsai <wens@xxxxxxxx>
---
Changes V1->V2:
* None

Changes V2->V3:
* Rewrite commit log

drivers/gpu/drm/sun4i/sun4i_tcon.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon.c b/drivers/gpu/drm/sun4i/sun4i_tcon.c
index e4b3bd0307ef..f949287d926c 100644
--- a/drivers/gpu/drm/sun4i/sun4i_tcon.c
+++ b/drivers/gpu/drm/sun4i/sun4i_tcon.c
@@ -491,7 +491,8 @@ static void sun4i_tcon0_mode_set_rgb(struct sun4i_tcon *tcon,
sun4i_tcon0_mode_set_common(tcon, mode);

/* Set dithering if needed */
- sun4i_tcon0_mode_set_dithering(tcon, tcon->panel->connector);
+ if (tcon->panel)
+ sun4i_tcon0_mode_set_dithering(tcon, tcon->panel->connector);

/* Adjust clock delay */
clk_delay = sun4i_tcon_get_clk_delay(mode, 0);
--
2.17.1