Commit 33b6a1f1 authored by Uladzislau Rezki (Sony)'s avatar Uladzislau Rezki (Sony) Committed by Joel Fernandes
Browse files

rcu: Return early if callback is not specified 



Currently the call_rcu() API does not check whether a callback
pointer is NULL. If NULL is passed, rcu_core() will try to invoke
it, resulting in NULL pointer dereference and a kernel crash.

To prevent this and improve debuggability, this patch adds a check
for NULL and emits a kernel stack trace to help identify a faulty
caller.

Signed-off-by: default avatarUladzislau Rezki (Sony) <urezki@gmail.com>
Reviewed-by: default avatarJoel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: default avatarJoel Fernandes <joelagnelf@nvidia.com>
parent 11313e2f

kernel/rcu/tree.c

+4 −0
Original line number Diff line number Diff line
@@ -3072,6 +3072,10 @@ __call_rcu_common(struct rcu_head *head, rcu_callback_t func, bool lazy_in) 
	/* Misaligned rcu_head! */

	WARN_ON_ONCE((unsigned long)head & (sizeof(void *) - 1));



	/* Avoid NULL dereference if callback is NULL. */

	if (WARN_ON_ONCE(!func))

		return;



	if (debug_rcu_head_queue(head)) {

		/*

		 * Probable double call_rcu(), so leak the callback.