[PATCH for-v7.5 07/11] rcu-tasks: Validate callback arguments

[Joel Fernandes <jfern@kernel.org>]

From: Kunwu Chan <kunwu.chan@gmail.com>

Check callback-head alignment and reject NULL callback
functions in the generic RCU Tasks callback registration path.

Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Kunwu Chan <chentao@kylinos.cn>
Reviewed-by: Joel Fernandes <jfern@kernel.org>
Signed-off-by: Joel Fernandes <jfern@kernel.org>
---
 kernel/rcu/tasks.h | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
index 0eec90464d64..a1883cf5b5d1 100644
--- a/kernel/rcu/tasks.h
+++ b/kernel/rcu/tasks.h
@@ -349,6 +349,13 @@ static void call_rcu_tasks_generic(struct rcu_head *rhp, rcu_callback_t func,
 	bool needwake;
 	struct rcu_tasks_percpu *rtpcp;
 
+	/* Misaligned rcu_head! */
+	WARN_ON_ONCE((unsigned long)rhp & (sizeof(void *) - 1));
+
+	/* Avoid NULL dereference if callback is NULL. */
+	if (WARN_ON_ONCE(!func))
+		return;
+
 	rhp->next = NULL;
 	rhp->func = func;
 	local_irq_save(flags);
-- 
2.54.0