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Subject: [PATCH 6/9] drm/vc4: Annotate struct vc4_perfmon with __counted_by
Date:   Fri, 22 Sep 2023 10:32:11 -0700
Message-Id: <20230922173216.3823169-6-keescook@chromium.org>
In-Reply-To: <20230922173110.work.084-kees@kernel.org>
References: <20230922173110.work.084-kees@kernel.org>
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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 vc4_perfmon.

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

Cc: Emma Anholt <emma@anholt.net>
Cc: Maxime Ripard <mripard@kernel.org>
Cc: David Airlie <airlied@gmail.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 drivers/gpu/drm/vc4/vc4_drv.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/vc4/vc4_drv.h b/drivers/gpu/drm/vc4/vc4_drv.h
index bf66499765fb..ab61e96e7e14 100644
--- a/drivers/gpu/drm/vc4/vc4_drv.h
+++ b/drivers/gpu/drm/vc4/vc4_drv.h
@@ -76,7 +76,7 @@ struct vc4_perfmon {
 	 * Note that counter values can't be reset, but you can fake a reset by
 	 * destroying the perfmon and creating a new one.
 	 */
-	u64 counters[];
+	u64 counters[] __counted_by(ncounters);
 };
 
 struct vc4_dev {
-- 
2.34.1