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 enetc_psfp_gate.

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

Cc: Claudiu Manoil <claudiu.man...@nxp.com>
Cc: Vladimir Oltean <vladimir.olt...@nxp.com>
Cc: "David S. Miller" <da...@davemloft.net>
Cc: Eric Dumazet <eduma...@google.com>
Cc: Jakub Kicinski <k...@kernel.org>
Cc: Paolo Abeni <pab...@redhat.com>
Cc: net...@vger.kernel.org
Signed-off-by: Kees Cook <keesc...@chromium.org>
---
 drivers/net/ethernet/freescale/enetc/enetc_qos.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/freescale/enetc/enetc_qos.c 
b/drivers/net/ethernet/freescale/enetc/enetc_qos.c
index 2513b44056c1..b65da49dd926 100644
--- a/drivers/net/ethernet/freescale/enetc/enetc_qos.c
+++ b/drivers/net/ethernet/freescale/enetc/enetc_qos.c
@@ -443,7 +443,7 @@ struct enetc_psfp_gate {
        u32 num_entries;
        refcount_t refcount;
        struct hlist_node node;
-       struct action_gate_entry entries[];
+       struct action_gate_entry entries[] __counted_by(num_entries);
 };
 
 /* Only enable the green color frame now
-- 
2.34.1


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