On Wed, Aug 07, 2024 at 11:55:00AM +0200, Thorsten Blum wrote:
> Add the __counted_by compiler attribute to the flexible array member
> records to improve access bounds-checking via CONFIG_UBSAN_BOUNDS and
> CONFIG_FORTIFY_SOURCE.
>
> Increment nr_records before adding a new pointer to the records array.
>
> Signed-off-by: Thorsten Blum <thorsten.blum@xxxxxxxxxx>
Reviewed-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
> ---
> kernel/rcu/tree.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> index e641cc681901..76d8d75dd8b3 100644
> --- a/kernel/rcu/tree.c
> +++ b/kernel/rcu/tree.c
> @@ -3227,7 +3227,7 @@ struct kvfree_rcu_bulk_data {
> struct list_head list;
> struct rcu_gp_oldstate gp_snap;
> unsigned long nr_records;
> - void *records[];
> + void *records[] __counted_by(nr_records);
> };
>
> /*
> @@ -3767,7 +3767,8 @@ add_ptr_to_bulk_krc_lock(struct kfree_rcu_cpu **krcp,
> }
>
> // Finally insert and update the GP for this page.
> - bnode->records[bnode->nr_records++] = ptr;
> + bnode->nr_records++;
> + bnode->records[bnode->nr_records - 1] = ptr;
> get_state_synchronize_rcu_full(&bnode->gp_snap);
> atomic_inc(&(*krcp)->bulk_count[idx]);
>
> --
> 2.45.2
>
