Re: [PATCH] drbd: Annotate struct fifo_buffer with __counted_by

[Gustavo A. R. Silva]

On 9/15/23 14:03, Kees Cook wrote:

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 fifo_buffer.

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

Cc: Philipp Reisner <philipp.reis...@linbit.com>
Cc: Lars Ellenberg <lars.ellenb...@linbit.com>
Cc: "Christoph Böhmwalder" <christoph.boehmwal...@linbit.com>
Cc: Jens Axboe <ax...@kernel.dk>
Cc: drbd-...@lists.linbit.com
Cc: linux-block@vger.kernel.org
Signed-off-by: Kees Cook <keesc...@chromium.org>

Reviewed-by: Gustavo A. R. Silva <gustavo...@kernel.org>

Thanks
--
Gustavo

---
  drivers/block/drbd/drbd_int.h | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/block/drbd/drbd_int.h b/drivers/block/drbd/drbd_int.h
index a30a5ed811be..7eecc53fae3d 100644
--- a/drivers/block/drbd/drbd_int.h
+++ b/drivers/block/drbd/drbd_int.h
@@ -553,7 +553,7 @@ struct fifo_buffer {
        unsigned int head_index;
        unsigned int size;
        int total; /* sum of all values */
-       int values[];
+       int values[] __counted_by(size);
  };
  extern struct fifo_buffer *fifo_alloc(unsigned int fifo_size);