[PATCH] hpet: Annotate struct hpets with __counted_by

[Kees Cook]

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 hpets.

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

Cc: Clemens Ladisch <clemens@xxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
 drivers/char/hpet.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/char/hpet.c b/drivers/char/hpet.c
index 3b2159416e62..807c389510de 100644
--- a/drivers/char/hpet.c
+++ b/drivers/char/hpet.c
@@ -92,7 +92,7 @@ struct hpets {
 	unsigned long hp_delta;
 	unsigned int hp_ntimer;
 	unsigned int hp_which;
-	struct hpet_dev hp_dev[];
+	struct hpet_dev hp_dev[] __counted_by(hp_ntimer);
 };
 
 static struct hpets *hpets;
-- 
2.34.1