From: Kees Cook <keescook@chromium.org>
To: Helge Deller <deller@gmx.de>
Cc: Kees Cook <keescook@chromium.org>,
	linux-fbdev@vger.kernel.org,
	dri-devel@lists.freedesktop.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] video: mmp: Annotate struct mmp_path with __counted_by
Date: Fri, 22 Sep 2023 10:51:41 -0700
Message-Id: <20230922175141.work.450-kees@kernel.org>
Precedence: bulk
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit

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 mmp_path.

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

Cc: Helge Deller <deller@gmx.de>
Cc: linux-fbdev@vger.kernel.org
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 include/video/mmp_disp.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/video/mmp_disp.h b/include/video/mmp_disp.h
index 77252cb46361..a722dcbf5073 100644
--- a/include/video/mmp_disp.h
+++ b/include/video/mmp_disp.h
@@ -231,7 +231,7 @@ struct mmp_path {
 
 	/* layers */
 	int overlay_num;
-	struct mmp_overlay overlays[];
+	struct mmp_overlay overlays[] __counted_by(overlay_num);
 };
 
 extern struct mmp_path *mmp_get_path(const char *name);
-- 
2.34.1