Hi Arnd,
Thanks for your patch.
> -----Original Message-----
> From: Arnd Bergmann <a...@kernel.org>
> Sent: Sunday, November 29, 2020 12:09 PM
> To: Chrisanthus, Anitha <anitha.chrisant...@intel.com>; Dea, Edmund J
> <edmund.j....@intel.com>; David Airlie <airl...@linux.ie>; Daniel Vetter
> <dan...@ffwll.ch>; Sam Ravnborg <s...@ravnborg.org>
> Cc: Arnd Bergmann <a...@arndb.de>; lkp <l...@intel.com>; dri-
> de...@lists.freedesktop.org; linux-ker...@vger.kernel.org
> Subject: [PATCH] drm/kmb: fix array bounds warning
>
> From: Arnd Bergmann <a...@arndb.de>
>
> gcc warns about an out-of-bounds access when the using nonzero
> values for 'plane_id' on kmb->plane_status:
>
> drivers/gpu/drm/kmb/kmb_plane.c: In function 'kmb_plane_atomic_disable':
> drivers/gpu/drm/kmb/kmb_plane.c:128:20: warning: array subscript 3 is
> above array bounds of 'struct layer_status[1]' [-Warray-bounds]
> 128 | kmb->plane_status[plane_id].ctrl = LCD_CTRL_GL2_ENABLE;
> | ~~~~~~~~~~~~~~~~~^~~~~~~~~~
> drivers/gpu/drm/kmb/kmb_plane.c:125:20: warning: array subscript 2 is
> above array bounds of 'struct layer_status[1]' [-Warray-bounds]
> 125 | kmb->plane_status[plane_id].ctrl = LCD_CTRL_GL1_ENABLE;
> | ~~~~~~~~~~~~~~~~~^~~~~~~~~~
> drivers/gpu/drm/kmb/kmb_plane.c:122:20: warning: array subscript 1 is
> above array bounds of 'struct layer_status[1]' [-Warray-bounds]
> 122 | kmb->plane_status[plane_id].ctrl = LCD_CTRL_VL2_ENABLE;
>
> Having the array truncated to one entry seems intentional, so add
> a range check before indexing it to make it clearer what is going
> on and shut up the warning.
>
> I received the warning from the kernel test robot after a private
> patch that turns on Warray-bounds unconditionally.
>
> Fixes: 7f7b96a8a0a1 ("drm/kmb: Add support for KeemBay Display")
> Reported-by: kernel test robot <l...@intel.com>
> Signed-off-by: Arnd Bergmann <a...@arndb.de>
> ---
> drivers/gpu/drm/kmb/kmb_plane.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/drivers/gpu/drm/kmb/kmb_plane.c
> b/drivers/gpu/drm/kmb/kmb_plane.c
> index 8448d1edb553..be8eea3830c1 100644
> --- a/drivers/gpu/drm/kmb/kmb_plane.c
> +++ b/drivers/gpu/drm/kmb/kmb_plane.c
> @@ -114,6 +114,9 @@ static void kmb_plane_atomic_disable(struct
> drm_plane *plane,
>
> kmb = to_kmb(plane->dev);
>
> + if (WARN_ON(plane_id >= KMB_MAX_PLANES))
> + return;
> +
Looks good.
Reviewed-by: Anitha Chrisanthus <anitha.chrisant...@intel.com>
> switch (plane_id) {
> case LAYER_0:
> kmb->plane_status[plane_id].ctrl = LCD_CTRL_VL1_ENABLE;
> --
> 2.27.0
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