[PATCH rcu 3/3] rcu: Annotate struct kvfree_rcu_bulk_data with __counted_by()

[neeraj . upadhyay]

From: Thorsten Blum <thorsten.b...@toblux.com>

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.b...@toblux.com>
Reviewed-by: "Gustavo A. R. Silva" <gustavo...@kernel.org>
Reviewed-by: "Uladzislau Rezki (Sony)" <ure...@gmail.com>
Reviewed-by: Paul E. McKenney <paul...@kernel.org>
Signed-off-by: Neeraj Upadhyay <neeraj.upadh...@kernel.org>
---
 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 0f41a81138dc..d5bf824159da 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]);
 
-- 
2.40.1