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

Commit Message

Neeraj Upadhyay Aug. 16, 2024, 7:22 a.m. UTC

From: Thorsten Blum <[e-mail]>

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 <[e-mail]>
Reviewed-by: "Gustavo A. R. Silva" <[e-mail]>
Reviewed-by: "Uladzislau Rezki (Sony)" <[e-mail]>
Reviewed-by: Paul E. McKenney <[e-mail]>
Signed-off-by: Neeraj Upadhyay <[e-mail]>
---
 kernel/rcu/tree.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

Patch

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]);