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 <[email protected]>
Cc: Bjorn Andersson <[email protected]>
Cc: Konrad Dybcio <[email protected]>
Cc: Nathan Chancellor <[email protected]>
Cc: Nick Desaulniers <[email protected]>
Cc: Tom Rix <[email protected]>
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Kees Cook <[email protected]>
---
 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


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