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, 63 insertions, 0 deletions

diff --git a/drivers/mfd/atc260x-i2c.c b/drivers/mfd/atc260x-i2c.c
new file mode 100644
index 000000000..fb53b0432
--- /dev/null
+++ b/drivers/mfd/atc260x-i2c.c
@@ -0,0 +1,63 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * I2C bus interface for ATC260x PMICs
+ *
+ * Copyright (C) 2019 Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
+ * Copyright (C) 2020 Cristian Ciocaltea <cristian.ciocaltea@gmail.com>
+ */
+
+#include <linux/i2c.h>
+#include <linux/mfd/atc260x/core.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/regmap.h>
+
+static int atc260x_i2c_probe(struct i2c_client *client)
+{
+	struct atc260x *atc260x;
+	struct regmap_config regmap_cfg;
+	int ret;
+
+	atc260x = devm_kzalloc(&client->dev, sizeof(*atc260x), GFP_KERNEL);
+	if (!atc260x)
+		return -ENOMEM;
+
+	atc260x->dev = &client->dev;
+	atc260x->irq = client->irq;
+
+	ret = atc260x_match_device(atc260x, &regmap_cfg);
+	if (ret)
+		return ret;
+
+	i2c_set_clientdata(client, atc260x);
+
+	atc260x->regmap = devm_regmap_init_i2c(client, &regmap_cfg);
+	if (IS_ERR(atc260x->regmap)) {
+		ret = PTR_ERR(atc260x->regmap);
+		dev_err(&client->dev, "failed to init regmap: %d\n", ret);
+		return ret;
+	}
+
+	return atc260x_device_probe(atc260x);
+}
+
+static const struct of_device_id atc260x_i2c_of_match[] = {
+	{ .compatible = "actions,atc2603c", .data = (void *)ATC2603C },
+	{ .compatible = "actions,atc2609a", .data = (void *)ATC2609A },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, atc260x_i2c_of_match);
+
+static struct i2c_driver atc260x_i2c_driver = {
+	.driver = {
+		.name = "atc260x",
+		.of_match_table	= atc260x_i2c_of_match,
+	},
+	.probe = atc260x_i2c_probe,
+};
+module_i2c_driver(atc260x_i2c_driver);
+
+MODULE_DESCRIPTION("ATC260x PMICs I2C bus interface");
+MODULE_AUTHOR("Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>");
+MODULE_AUTHOR("Cristian Ciocaltea <cristian.ciocaltea@gmail.com>");
+MODULE_LICENSE("GPL");