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, 32 insertions, 0 deletions

diff --git a/drivers/soc/imx/imx93-src.c b/drivers/soc/imx/imx93-src.c
new file mode 100644
index 000000000..f1c2e22d5
--- /dev/null
+++ b/drivers/soc/imx/imx93-src.c
@@ -0,0 +1,32 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2022 NXP
+ */
+
+#include <linux/module.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+
+static int imx93_src_probe(struct platform_device *pdev)
+{
+	return devm_of_platform_populate(&pdev->dev);
+}
+
+static const struct of_device_id imx93_src_ids[] = {
+	{ .compatible = "fsl,imx93-src" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, imx93_src_ids);
+
+static struct platform_driver imx93_src_driver = {
+	.driver = {
+		.name	= "imx93_src",
+		.of_match_table = imx93_src_ids,
+	},
+	.probe = imx93_src_probe,
+};
+module_platform_driver(imx93_src_driver);
+
+MODULE_AUTHOR("Peng Fan <peng.fan@nxp.com>");
+MODULE_DESCRIPTION("NXP i.MX93 src driver");
+MODULE_LICENSE("GPL");