selftests/bpf: Reject graph kptr use after RCU unlockgrafted

Add a sleepable verifier test that loads a graph-node local kptr in an
explicit RCU read-side critical section, then passes its node to
bpf_rbtree_remove() after the section ends.

Before the verifier fix, the stale NON_OWN_REF flag makes the node look like
a live borrowed reference and the program is accepted. After the fix, the
pointer is demoted without NON_OWN_REF and the graph kfunc argument is
rejected.

Also exercise a graph kptr loaded while a spin lock provides implicit RCU
protection. The pointer must be invalidated when the lock is released, which
guards the required ordering between non-owning-reference invalidation and
RCU demotion.

Update the existing fault-protected load test state description. The
post-unlock pointer no longer carries NON_OWN_REF, but remains readable
because the load is rewritten to use BPF_PROBE_MEM.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20260904084325.52250-7-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 29 insertions, 0 deletions

diff --git a/include/kunit/fwnode.h b/include/kunit/fwnode.h
new file mode 100644
index 000000000..e250bb87e
--- /dev/null
+++ b/include/kunit/fwnode.h
@@ -0,0 +1,29 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * KUnit resource management helpers for firmware nodes.
+ *
+ * Copyright (C) Qualcomm Technologies, Inc. and/or its subsidiaries
+ */
+
+#ifndef _KUNIT_FWNODE_H
+#define _KUNIT_FWNODE_H
+
+struct device;
+struct fwnode_handle;
+struct kunit;
+struct property_entry;
+struct software_node;
+
+struct fwnode_handle *
+kunit_fwnode_create_software_node(struct kunit *test,
+				  const struct property_entry *properties,
+				  const struct fwnode_handle *parent);
+struct fwnode_handle *
+kunit_software_node_register(struct kunit *test,
+			     const struct software_node *node);
+int kunit_software_node_register_node_group(struct kunit *test,
+					    const struct software_node *const *nodes);
+int kunit_device_add_software_node(struct kunit *test, struct device *dev,
+				   const struct software_node *node);
+
+#endif /* _KUNIT_FWNODE_H */