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 smt_data.

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

Cc: Raju Rangoju <[email protected]>
Cc: "David S. Miller" <[email protected]>
Cc: Eric Dumazet <[email protected]>
Cc: Jakub Kicinski <[email protected]>
Cc: Paolo Abeni <[email protected]>
Cc: [email protected]
Signed-off-by: Kees Cook <[email protected]>
---
 drivers/net/ethernet/chelsio/cxgb4/smt.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/chelsio/cxgb4/smt.h 
b/drivers/net/ethernet/chelsio/cxgb4/smt.h
index 541249d78914..109c1dff563a 100644
--- a/drivers/net/ethernet/chelsio/cxgb4/smt.h
+++ b/drivers/net/ethernet/chelsio/cxgb4/smt.h
@@ -66,7 +66,7 @@ struct smt_entry {
 struct smt_data {
        unsigned int smt_size;
        rwlock_t lock;
-       struct smt_entry smtab[];
+       struct smt_entry smtab[] __counted_by(smt_size);
 };
 
 struct smt_data *t4_init_smt(void);
-- 
2.34.1


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