[PATCH] platform/chrome: wilco_ec: Annotate struct ec_event_queue 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 ec_event_queue.

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

Cc: Benson Leung <bleung@xxxxxxxxxxxx>
Cc: Tzung-Bi Shih <tzungbi@xxxxxxxxxx>
Cc: Dawei Li <set_pte_at@xxxxxxxxxxx>
Cc: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
Cc: Maximilian Luz <luzmaximilian@xxxxxxxxx>
Cc: "Uwe Kleine-König" <u.kleine-koenig@xxxxxxxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Jiang Jian <jiangjian@xxxxxxxxxx>
Cc: chrome-platform@xxxxxxxxxxxxxxx
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
 drivers/platform/chrome/wilco_ec/event.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/platform/chrome/wilco_ec/event.c b/drivers/platform/chrome/wilco_ec/event.c
index a40f60bcefb6..f80a7c83cfba 100644
--- a/drivers/platform/chrome/wilco_ec/event.c
+++ b/drivers/platform/chrome/wilco_ec/event.c
@@ -95,7 +95,7 @@ struct ec_event_queue {
 	int capacity;
 	int head;
 	int tail;
-	struct ec_event *entries[];
+	struct ec_event *entries[] __counted_by(capacity);
 };
 
 /* Maximum number of events to store in ec_event_queue */
-- 
2.34.1