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, 119 insertions, 0 deletions

diff --git a/drivers/hwmon/adt7410.c b/drivers/hwmon/adt7410.c
new file mode 100644
index 000000000..6629b83aa
--- /dev/null
+++ b/drivers/hwmon/adt7410.c
@@ -0,0 +1,119 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * ADT7410/ADT7420 digital temperature sensor driver
+ *
+ * Copyright 2012-2013 Analog Devices Inc.
+ *   Author: Lars-Peter Clausen <lars@metafoo.de>
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/i2c.h>
+#include <linux/regmap.h>
+
+#include "adt7x10.h"
+
+static bool adt7410_regmap_is_volatile(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case ADT7X10_TEMPERATURE:
+	case ADT7X10_STATUS:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static int adt7410_reg_read(void *context, unsigned int reg, unsigned int *val)
+{
+	struct i2c_client *client = context;
+	int regval;
+
+	switch (reg) {
+	case ADT7X10_TEMPERATURE:
+	case ADT7X10_T_ALARM_HIGH:
+	case ADT7X10_T_ALARM_LOW:
+	case ADT7X10_T_CRIT:
+		regval = i2c_smbus_read_word_swapped(client, reg);
+		break;
+	default:
+		regval = i2c_smbus_read_byte_data(client, reg);
+		break;
+	}
+	if (regval < 0)
+		return regval;
+	*val = regval;
+	return 0;
+}
+
+static int adt7410_reg_write(void *context, unsigned int reg, unsigned int val)
+{
+	struct i2c_client *client = context;
+	int ret;
+
+	switch (reg) {
+	case ADT7X10_TEMPERATURE:
+	case ADT7X10_T_ALARM_HIGH:
+	case ADT7X10_T_ALARM_LOW:
+	case ADT7X10_T_CRIT:
+		ret = i2c_smbus_write_word_swapped(client, reg, val);
+		break;
+	default:
+		ret = i2c_smbus_write_byte_data(client, reg, val);
+		break;
+	}
+	return ret;
+}
+
+static const struct regmap_config adt7410_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 16,
+	.max_register = ADT7X10_ID,
+	.cache_type = REGCACHE_MAPLE,
+	.volatile_reg = adt7410_regmap_is_volatile,
+	.reg_read = adt7410_reg_read,
+	.reg_write = adt7410_reg_write,
+};
+
+static int adt7410_i2c_probe(struct i2c_client *client)
+{
+	struct regmap *regmap;
+
+	regmap = devm_regmap_init(&client->dev, NULL, client,
+				  &adt7410_regmap_config);
+	if (IS_ERR(regmap))
+		return PTR_ERR(regmap);
+
+	return adt7x10_probe(&client->dev, client->name, client->irq, regmap);
+}
+
+static const struct i2c_device_id adt7410_ids[] = {
+	{ .name = "adt7410" },
+	{ .name = "adt7420" },
+	{ .name = "adt7422" },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, adt7410_ids);
+
+static const struct of_device_id adt7410_of_match[] = {
+	{ .compatible = "adi,adt7410" },
+	{ .compatible = "adi,adt7420" },
+	{ .compatible = "adi,adt7422" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, adt7410_of_match);
+
+static struct i2c_driver adt7410_driver = {
+	.driver = {
+		.name	= "adt7410",
+		.pm	= pm_sleep_ptr(&adt7x10_dev_pm_ops),
+		.of_match_table = adt7410_of_match,
+	},
+	.probe		= adt7410_i2c_probe,
+	.id_table	= adt7410_ids,
+};
+module_i2c_driver(adt7410_driver);
+
+MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
+MODULE_DESCRIPTION("ADT7410/AD7420 driver");
+MODULE_LICENSE("GPL");