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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id l12sm393581pff.182.2021.08.25.11.18.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 25 Aug 2021 11:18:09 -0700 (PDT) From: Kees Cook To: Anitha Chrisanthus Cc: Kees Cook , Edmund Dea , David Airlie , Daniel Vetter , dri-devel@lists.freedesktop.org, Sam Ravnborg , linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: [PATCH] drm/kmb: Avoid warnings on impossible plane_id Date: Wed, 25 Aug 2021 11:18:07 -0700 Message-Id: <20210825181807.1138053-1-keescook@chromium.org> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=2468; h=from:subject; bh=ayGL3nTtXBhmXO1+dOFqn7dP3xjc2moHEVzr5eS5hbQ=; b=owEBbQKS/ZANAwAKAYly9N/cbcAmAcsmYgBhJoles+iSi8/TcrgLqrEPD56glc8HYMihckLxnx8C SpNgn/qJAjMEAAEKAB0WIQSlw/aPIp3WD3I+bhOJcvTf3G3AJgUCYSaJXgAKCRCJcvTf3G3AJmhTD/ 4/cuvF+pSPHIc+WlDe0LjwPRoQ4vqJ222edu1HXyrfThq8nwl8bV18+27ltqyvu9rpQVHmWRcyJAJX uoKim0qwDeqvk5oz5MNkMBVKKkrOk5M5+3LOrfTsyaGsTVriq5d8AfRpNdlkLN0e8aHn4WwqE5Fe2R L615qyAeyupg39I6tLO3QYVc3+EINhOWXmOeoDCoHxY2j66qO2PSEPkqVyaf0EZDl6PBZiFdoR/pNT BbBVGYsbO6y9doT9Yls5/mJobgFnhrT3arOx0utGohkwJMmdGVzV4vHrMlu1RcilF/2QnlgzKvV+ic jBN2yQHN7CQME0dF2VMRw9fh3qEbzNXyrysHbCa3i4EZm2obqc3tDLwjffgNpwo0r3zYPO0CpmD1Tg C8HH/v32xIC1kdzwho9BX6PW/OHD8hQ9y6AEDkhiQDw9Q0+YlupHAHLSVFzicrYOHOfbAIcExDhOe0 90aqMZz/CT0L89g2IxzbCYWv3bmdKcDNsF0h0B3HsrZCFNp6mIz9oZXGeHP2rOqDP+kBBKAzHJLtRg yRBMNNH4ed0CkXo8BDCAsXDi9QNT6lJFQhHOud7BWOZekf5g9hZSQwCA7KdjIKHtVfSuogK+AU5S0y iW5tjeTqhto9Km8GPK6DDgtDKRzfSsWa51eL/sPY6Xv7I4eVvBt2UI8nW+QA== X-Developer-Key: i=keescook@chromium.org; a=openpgp; fpr=A5C3F68F229DD60F723E6E138972F4DFDC6DC026 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 Cc: Edmund Dea Cc: David Airlie Cc: Daniel Vetter Cc: dri-devel@lists.freedesktop.org Fixes: 7f7b96a8a0a1 ("drm/kmb: Add support for KeemBay Display") Signed-off-by: Kees Cook --- 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