hpet: Annotate struct hpets with __counted_by

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@ladisch.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Link: https://lore.kernel.org/r/20230922175348.work.056-kees@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/char/hpet.c b/drivers/char/hpet.c
index ee71376f174b70dbdf7d0982945c5ba3a45926f4..0176a76cf0fe2b74675af9600162b74a15d07b1a 100644 (file)
--- a/drivers/char/hpet.c
+++ b/drivers/char/hpet.c
@@ -111,7 +111,7 @@ 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;