diff mbox series

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

Message ID 20181005215951.99003-2-giulio.benetti@micronovasrl.com (mailing list archive)
State New, archived
Headers show
Series [v3,1/2] drm/sun4i: tcon: fix check of tcon->panel null pointer | expand

Commit Message

Giulio Benetti Oct. 5, 2018, 9:59 p.m. UTC 
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@micronovasrl.com>
Fixes: f11adcecbd5f ("drm/sun4i: tcon: Add dithering support for
                      RGB565/RGB666 LCD panels")
Reviewed-by: Chen-Yu Tsai <wens@csie.org>
---
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(-)

Comments

Maxime Ripard Oct. 8, 2018, 9:21 a.m. UTC | #1 
On Fri, Oct 05, 2018 at 11:59:51PM +0200, Giulio Benetti wrote:
> 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@micronovasrl.com>
> Fixes: f11adcecbd5f ("drm/sun4i: tcon: Add dithering support for
>                       RGB565/RGB666 LCD panels")
> Reviewed-by: Chen-Yu Tsai <wens@csie.org>

Applied both, thanks!
Maxime
Chen-Yu Tsai Oct. 12, 2018, 10:03 a.m. UTC | #2 
On Mon, Oct 8, 2018 at 5:21 PM Maxime Ripard <maxime.ripard@bootlin.com> wrote:
>
> On Fri, Oct 05, 2018 at 11:59:51PM +0200, Giulio Benetti wrote:
> > 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@micronovasrl.com>
> > Fixes: f11adcecbd5f ("drm/sun4i: tcon: Add dithering support for
> >                       RGB565/RGB666 LCD panels")
> > Reviewed-by: Chen-Yu Tsai <wens@csie.org>
>
> Applied both, thanks!

I think this one could have been applied to drm-misc-next-fixes,
as the bug was only recently introduced.

We'll have to make sure it gets backported somehow.

ChenYu
Icenowy Zheng Nov. 5, 2018, 1:23 p.m. UTC | #3 
在 2018-10-08一的 11:21 +0200，Maxime Ripard写道：
> On Fri, Oct 05, 2018 at 11:59:51PM +0200, Giulio Benetti wrote:
> > 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@micronovasrl.com>
> > Fixes: f11adcecbd5f ("drm/sun4i: tcon: Add dithering support for
> >                       RGB565/RGB666 LCD panels")
> > Reviewed-by: Chen-Yu Tsai <wens@csie.org>
> 
> Applied both, thanks!

Please bring them to 4.20.

Currently in 4.20-rc1, bridge support of sun4i-drm is broken because of
this problem.

> Maxime
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
Maxime Ripard Nov. 6, 2018, 3:57 p.m. UTC | #4 
On Mon, Nov 05, 2018 at 09:23:08PM +0800, Icenowy Zheng wrote:
> 在 2018-10-08一的 11:21 +0200，Maxime Ripard写道：
> > On Fri, Oct 05, 2018 at 11:59:51PM +0200, Giulio Benetti wrote:
> > > 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@micronovasrl.com>
> > > Fixes: f11adcecbd5f ("drm/sun4i: tcon: Add dithering support for
> > >                       RGB565/RGB666 LCD panels")
> > > Reviewed-by: Chen-Yu Tsai <wens@csie.org>
> > 
> > Applied both, thanks!
> 
> Please bring them to 4.20.
> 
> Currently in 4.20-rc1, bridge support of sun4i-drm is broken because of
> this problem.

I've merged them in drm-misc-fixes, thanks!

Maxime
diff mbox series

Patch

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);