From: "Chrisanthus, Anitha" <anitha.chrisanthus@intel.com>
To: Kees Cook <keescook@chromium.org>
Cc: "Dea, Edmund J" <edmund.j.dea@intel.com>,
David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>,
"dri-devel@lists.freedesktop.org"
<dri-devel@lists.freedesktop.org>,
Sam Ravnborg <sam@ravnborg.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-hardening@vger.kernel.org"
<linux-hardening@vger.kernel.org>
Subject: RE: [PATCH] drm/kmb: Avoid warnings on impossible plane_id
Date: Wed, 25 Aug 2021 20:44:29 +0000 [thread overview]
Message-ID: <BY5PR11MB4182ABD607EB99C1F68777928CC69@BY5PR11MB4182.namprd11.prod.outlook.com> (raw)
In-Reply-To: <20210825181807.1138053-1-keescook@chromium.org>
Hi Kees,
Thanks for your patch.
The switch statement is needed for multiple planes which is already approved in this patch series.
https://patchwork.kernel.org/project/dri-devel/patch/20210728003126.1425028-13-anitha.chrisanthus@intel.com/
This patch has dependencies on the previous patches in this series, and we are waiting for reviews on those before this can be checked in.
Thanks,
Anitha
> -----Original Message-----
> From: Kees Cook <keescook@chromium.org>
> Sent: Wednesday, August 25, 2021 11:18 AM
> To: Chrisanthus, Anitha <anitha.chrisanthus@intel.com>
> Cc: Kees Cook <keescook@chromium.org>; Dea, Edmund J
> <edmund.j.dea@intel.com>; David Airlie <airlied@linux.ie>; Daniel Vetter
> <daniel@ffwll.ch>; dri-devel@lists.freedesktop.org; Sam Ravnborg
> <sam@ravnborg.org>; linux-kernel@vger.kernel.org; linux-
> hardening@vger.kernel.org
> Subject: [PATCH] drm/kmb: Avoid warnings on impossible plane_id
>
> KMB_MAX_PLANES is defined as 1, yet kmb_plane_atomic_disable() had code
> for writing beyond 1. It is gated by a WARN_ON() that would skip it,
> though, but under some compiler versions, poor Dead Code Elimination
> wasn't optimizing away the unused switch cases, leading to array bounds
> warnings when building with -Warray-bounds:
>
> drivers/gpu/drm/kmb/kmb_plane.c:135:20: warning: array subscript 3 is
> above array bounds of 'struct layer_status[1]' [-Warray-bounds]
> drivers/gpu/drm/kmb/kmb_plane.c:132:20: warning: array subscript 2 is
> above array bounds of 'struct layer_status[1]' [-Warray-bounds]
> drivers/gpu/drm/kmb/kmb_plane.c:129:20: warning: array subscript 1 is
> above array bounds of 'struct layer_status[1]' [-Warray-bounds]
>
> Instead, just remove the switch statement entirely and adjust the index
> type to match the struct "id" member.
>
> Cc: Anitha Chrisanthus <anitha.chrisanthus@intel.com>
> Cc: Edmund Dea <edmund.j.dea@intel.com>
> Cc: David Airlie <airlied@linux.ie>
> Cc: Daniel Vetter <daniel@ffwll.ch>
> Cc: dri-devel@lists.freedesktop.org
> Fixes: 7f7b96a8a0a1 ("drm/kmb: Add support for KeemBay Display")
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
> drivers/gpu/drm/kmb/kmb_plane.c | 18 ++----------------
> 1 file changed, 2 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/gpu/drm/kmb/kmb_plane.c
> b/drivers/gpu/drm/kmb/kmb_plane.c
> index ecee6782612d..3d46e756f2fe 100644
> --- a/drivers/gpu/drm/kmb/kmb_plane.c
> +++ b/drivers/gpu/drm/kmb/kmb_plane.c
> @@ -113,7 +113,7 @@ static void kmb_plane_atomic_disable(struct
> drm_plane *plane,
> struct drm_atomic_state *state)
> {
> struct kmb_plane *kmb_plane = to_kmb_plane(plane);
> - int plane_id = kmb_plane->id;
> + unsigned char plane_id = kmb_plane->id;
> struct kmb_drm_private *kmb;
>
> kmb = to_kmb(plane->dev);
> @@ -121,21 +121,7 @@ static void kmb_plane_atomic_disable(struct
> drm_plane *plane,
> if (WARN_ON(plane_id >= KMB_MAX_PLANES))
> return;
>
> - switch (plane_id) {
> - case LAYER_0:
> - kmb->plane_status[plane_id].ctrl = LCD_CTRL_VL1_ENABLE;
> - break;
> - case LAYER_1:
> - kmb->plane_status[plane_id].ctrl = LCD_CTRL_VL2_ENABLE;
> - break;
> - case LAYER_2:
> - kmb->plane_status[plane_id].ctrl = LCD_CTRL_GL1_ENABLE;
> - break;
> - case LAYER_3:
> - kmb->plane_status[plane_id].ctrl = LCD_CTRL_GL2_ENABLE;
> - break;
> - }
> -
> + kmb->plane_status[plane_id].ctrl = LCD_CTRL_VL1_ENABLE;
> kmb->plane_status[plane_id].disable = true;
> }
>
> --
> 2.30.2
next prev parent reply other threads:[~2021-08-25 20:44 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-25 18:18 [PATCH] drm/kmb: Avoid warnings on impossible plane_id Kees Cook
2021-08-25 20:44 ` Chrisanthus, Anitha [this message]
2021-09-07 17:32 ` Chrisanthus, Anitha
2021-09-07 18:11 ` Kees Cook
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=BY5PR11MB4182ABD607EB99C1F68777928CC69@BY5PR11MB4182.namprd11.prod.outlook.com \
--to=anitha.chrisanthus@intel.com \
--cc=airlied@linux.ie \
--cc=daniel@ffwll.ch \
--cc=dri-devel@lists.freedesktop.org \
--cc=edmund.j.dea@intel.com \
--cc=keescook@chromium.org \
--cc=linux-hardening@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=sam@ravnborg.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).