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 qcom_smem.

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

Cc: Andy Gross <agross@kernel.org>
Cc: Bjorn Andersson <andersson@kernel.org>
Cc: Konrad Dybcio <konrad.dybcio@linaro.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Tom Rix <trix@redhat.com>
Cc: linux-arm-msm@vger.kernel.org
Cc: llvm@lists.linux.dev
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 drivers/soc/qcom/smem.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/soc/qcom/smem.c b/drivers/soc/qcom/smem.c
index d4a89d2bb43b..4ce9cf1477ac 100644
--- a/drivers/soc/qcom/smem.c
+++ b/drivers/soc/qcom/smem.c
@@ -285,7 +285,7 @@ struct qcom_smem {
 	struct smem_partition partitions[SMEM_HOST_COUNT];
 
 	unsigned num_regions;
-	struct smem_region regions[];
+	struct smem_region regions[] __counted_by(num_regions);
 };
 
 static void *
-- 
2.34.1

On Fri, 22 Sep 2023 10:54:14 -0700, Kees Cook wrote:
> 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 qcom_smem.
> 
> [...]

Applied, thanks!

[1/1] soc: qcom: smem: Annotate struct qcom_smem with __counted_by
      commit: 433ce46a97116f431ee114b4607143860aad4054

Best regards,
-- 
Bjorn Andersson <andersson@kernel.org>