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, 61 insertions, 0 deletions

diff --git a/drivers/dpll/zl3073x/i2c.c b/drivers/dpll/zl3073x/i2c.c
new file mode 100644
index 000000000..4a23340e2
--- /dev/null
+++ b/drivers/dpll/zl3073x/i2c.c
@@ -0,0 +1,61 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <linux/dev_printk.h>
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+
+#include "core.h"
+
+static int zl3073x_i2c_probe(struct i2c_client *client)
+{
+	struct device *dev = &client->dev;
+	struct zl3073x_dev *zldev;
+
+	zldev = zl3073x_devm_alloc(dev);
+	if (IS_ERR(zldev))
+		return PTR_ERR(zldev);
+
+	zldev->regmap = devm_regmap_init_i2c(client, &zl3073x_regmap_config);
+	if (IS_ERR(zldev->regmap))
+		return dev_err_probe(dev, PTR_ERR(zldev->regmap),
+				     "Failed to initialize regmap\n");
+
+	return zl3073x_dev_probe(zldev);
+}
+
+static const struct i2c_device_id zl3073x_i2c_id[] = {
+	{ .name = "zl30731" },
+	{ .name = "zl30732" },
+	{ .name = "zl30733" },
+	{ .name = "zl30734" },
+	{ .name = "zl30735" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(i2c, zl3073x_i2c_id);
+
+static const struct of_device_id zl3073x_i2c_of_match[] = {
+	{ .compatible = "microchip,zl30731" },
+	{ .compatible = "microchip,zl30732" },
+	{ .compatible = "microchip,zl30733" },
+	{ .compatible = "microchip,zl30734" },
+	{ .compatible = "microchip,zl30735" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, zl3073x_i2c_of_match);
+
+static struct i2c_driver zl3073x_i2c_driver = {
+	.driver = {
+		.name = "zl3073x-i2c",
+		.of_match_table = zl3073x_i2c_of_match,
+	},
+	.probe = zl3073x_i2c_probe,
+	.id_table = zl3073x_i2c_id,
+};
+module_i2c_driver(zl3073x_i2c_driver);
+
+MODULE_AUTHOR("Ivan Vecera <ivecera@redhat.com>");
+MODULE_DESCRIPTION("Microchip ZL3073x I2C driver");
+MODULE_IMPORT_NS("ZL3073X");
+MODULE_LICENSE("GPL");