Re: [PATCH v2 2/2] drm/sun4i: tcon: prevent tcon->panel dereference if null

2018-10-05 Thread Giulio Benetti 

Hi,

Il 04/10/2018 21:56, Maxime Ripard ha scritto:

On Wed, Oct 03, 2018 at 04:24:58PM +0200, Giulio Benetti wrote:

If using tcon with VGA,


We don't have support for VGA at the moment. Or are you talking about
using a VGA bridge?


You're right, in general VGA is not the point.
tcon->panel is retrieved by drm_of_find_panel_or_bridge() and panel can 
be present or not.



tcon->panel will be null(0), this will cause segmentation fault when
trying to dereference tcon->panel->connector.


It's not a segmentation fault, but a null pointer dereference. And
that case will also happen with bridges.


Right.

Going to improve/rewrite commit logs and submit v2 patchset.

Thanks for reviewing.

Best regards
--
Giulio Benetti
CTO

MICRONOVA SRL
Sede: Via A. Niedda 3 - 35010 Vigonza (PD)
Tel. 049/8931563 - Fax 049/8931346
Cod.Fiscale - P.IVA 02663420285
Capitale Sociale € 26.000 i.v.
Iscritta al Reg. Imprese di Padova N. 02663420285
Numero R.E.A. 258642
___
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel

Re: [PATCH v2 2/2] drm/sun4i: tcon: prevent tcon->panel dereference if null

2018-10-04 Thread Maxime Ripard 
On Wed, Oct 03, 2018 at 04:24:58PM +0200, Giulio Benetti wrote:
> If using tcon with VGA,

We don't have support for VGA at the moment. Or are you talking about
using a VGA bridge?

> tcon->panel will be null(0), this will cause segmentation fault when
> trying to dereference tcon->panel->connector.

It's not a segmentation fault, but a null pointer dereference. And
that case will also happen with bridges.

Maxime

-- 
Maxime Ripard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com


signature.asc
Description: PGP signature
___
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel

[PATCH v2 2/2] drm/sun4i: tcon: prevent tcon->panel dereference if null

2018-10-03 Thread Giulio Benetti 
If using tcon with VGA, tcon->panel will be null(0), this will cause
segmentation fault when trying to dereference tcon->panel->connector.

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

Signed-off-by: Giulio Benetti 
Fixes: f11adcecbd5f ("drm/sun4i: tcon: Add dithering support for
  RGB565/RGB666 LCD panels")
Reviewed-by: Chen-Yu Tsai 
---
Changes V1->V2:
* none

 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

___
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel