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From:   Kees Cook <keescook@chromium.org>
To:     Pavel Machek <pavel@ucw.cz>
Cc:     Kees Cook <keescook@chromium.org>, Lee Jones <lee@kernel.org>,
        linux-leds@vger.kernel.org, Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Tom Rix <trix@redhat.com>, linux-kernel@vger.kernel.org,
        llvm@lists.linux.dev, linux-hardening@vger.kernel.org
Subject: [PATCH] leds: aw200xx: Annotate struct aw200xx with __counted_by
Date:   Fri, 15 Sep 2023 13:09:39 -0700
Message-Id: <20230915200938.never.767-kees@kernel.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

Prepare for the coming implementation by GCC and Clang of the __counted_by
attribute. Flexible array members annotated with __counted_by can have
their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS
(for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
functions).

As found with Coccinelle[1], add __counted_by for struct aw200xx.

[1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci

Cc: Pavel Machek <pavel@ucw.cz>
Cc: Lee Jones <lee@kernel.org>
Cc: linux-leds@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 drivers/leds/leds-aw200xx.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/leds/leds-aw200xx.c b/drivers/leds/leds-aw200xx.c
index 691a743cc9b0..4d517cace3e7 100644
--- a/drivers/leds/leds-aw200xx.c
+++ b/drivers/leds/leds-aw200xx.c
@@ -112,7 +112,7 @@ struct aw200xx {
 	struct mutex mutex;
 	u32 num_leds;
 	u32 display_rows;
-	struct aw200xx_led leds[];
+	struct aw200xx_led leds[] __counted_by(num_leds);
 };
 
 static ssize_t dim_show(struct device *dev, struct device_attribute *devattr,
-- 
2.34.1