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

neeraj.upadhyay
2024-08-16T07:23:55Z

From: Thorsten Blum <thorsten.blum@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.blum@toblux.com>
Reviewed-by: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Reviewed-by: "Uladzislau Rezki (Sony)" <urezki@gmail.com>
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Neeraj Upadhyay <neeraj.upadhyay@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