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, 146 insertions, 0 deletions

diff --git a/lib/kunit/fwnode.c b/lib/kunit/fwnode.c
new file mode 100644
index 000000000..a58ce0984
--- /dev/null
+++ b/lib/kunit/fwnode.c
@@ -0,0 +1,146 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) Qualcomm Technologies, Inc. and/or its subsidiaries
+ */
+
+#include <kunit/fwnode.h>
+#include <kunit/test.h>
+
+#include <linux/fwnode.h>
+#include <linux/property.h>
+
+KUNIT_DEFINE_ACTION_WRAPPER(fwnode_remove_software_node_wrapper,
+			    fwnode_remove_software_node,
+			    struct fwnode_handle *);
+
+/**
+ * kunit_fwnode_create_software_node() - Create a kunit-managed software node
+ * @test: Test context
+ * @properties: Properties to use to create the new software node
+ * @parent: Parent of this software node
+ *
+ * Create a test-managed software node and return its firmware node handle.
+ * The software node is removed after the test case completes.
+ *
+ * Returns:
+ * Firmware node handle of the newly created software node or IS_ERR() on
+ * failure.
+ */
+struct fwnode_handle *
+kunit_fwnode_create_software_node(struct kunit *test,
+				  const struct property_entry *properties,
+				  const struct fwnode_handle *parent)
+{
+	struct fwnode_handle *fwnode;
+	int ret;
+
+	fwnode = fwnode_create_software_node(properties, parent);
+	if (IS_ERR(fwnode))
+		return fwnode;
+
+	ret = kunit_add_action_or_reset(test, fwnode_remove_software_node_wrapper,
+					fwnode);
+	if (ret)
+		return ERR_PTR(ret);
+
+	return fwnode;
+}
+EXPORT_SYMBOL_GPL(kunit_fwnode_create_software_node);
+
+KUNIT_DEFINE_ACTION_WRAPPER(software_node_unregister_wrapper,
+			    software_node_unregister,
+			    const struct software_node *);
+
+/**
+ * kunit_software_node_register() - Register a kunit-managed software node
+ * @test: Test context
+ * @swnode: Software node to register
+ *
+ * Register a test-managed software node and return its firmware node handle.
+ * The software node is unregistered after the test case completes.
+ *
+ * Returns:
+ * Firmware node handle of the registered software node or IS_ERR() on failure.
+ */
+struct fwnode_handle *
+kunit_software_node_register(struct kunit *test,
+			     const struct software_node *swnode)
+{
+	struct fwnode_handle *fwnode;
+	int ret;
+
+	ret = software_node_register(swnode);
+	if (ret)
+		return ERR_PTR(ret);
+
+	fwnode = software_node_fwnode(swnode);
+	if (WARN_ON(!fwnode))
+		return ERR_PTR(-ENOENT);
+
+	ret = kunit_add_action_or_reset(test, software_node_unregister_wrapper,
+					(void *)swnode);
+	if (ret)
+		return ERR_PTR(ret);
+
+	return fwnode;
+}
+EXPORT_SYMBOL_GPL(kunit_software_node_register);
+
+KUNIT_DEFINE_ACTION_WRAPPER(software_node_unregister_node_group_wrapper,
+			    software_node_unregister_node_group,
+			    const struct software_node *const *);
+
+/**
+ * kunit_software_node_register_node_group() - Register a kunit-managed software node group
+ * @test: Test context
+ * @nodes: Software node group to register
+ *
+ * Register a test-managed software node group. The nodes are unregistered
+ * after the test case completes.
+ *
+ * Returns:
+ * 0 on success, negative error number on failure.
+ */
+int kunit_software_node_register_node_group(struct kunit *test,
+					    const struct software_node *const *nodes)
+{
+	int ret;
+
+	ret = software_node_register_node_group(nodes);
+	if (ret)
+		return ret;
+
+	return kunit_add_action_or_reset(test, software_node_unregister_node_group_wrapper,
+					 (void *)nodes);
+}
+EXPORT_SYMBOL_GPL(kunit_software_node_register_node_group);
+
+KUNIT_DEFINE_ACTION_WRAPPER(device_remove_software_node_wrapper,
+			    device_remove_software_node,
+			    struct device *);
+
+/**
+ * kunit_device_add_software_node() - Assign a kunit-managed software node to a device
+ * @test: Test context
+ * @dev: Device to assign the software node for
+ * @node: The software node to assign
+ *
+ * Make @node the secondary firmware node of @dev. If @dev has no primary
+ * firmware node, @node will become the primary node. The software node will
+ * be automatically removed from @dev when the test case completes.
+ *
+ * Returns:
+ * 0 on success, negative error number on failure.
+ */
+int kunit_device_add_software_node(struct kunit *test, struct device *dev,
+				   const struct software_node *node)
+{
+	int ret;
+
+	ret = device_add_software_node(dev, node);
+	if (ret)
+		return ret;
+
+	return kunit_add_action_or_reset(test, device_remove_software_node_wrapper, dev);
+}
+EXPORT_SYMBOL_GPL(kunit_device_add_software_node);