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, 127 insertions, 0 deletions

diff --git a/drivers/mfd/arizona-i2c.c b/drivers/mfd/arizona-i2c.c
new file mode 100644
index 000000000..10e76fc8f
--- /dev/null
+++ b/drivers/mfd/arizona-i2c.c
@@ -0,0 +1,127 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Arizona-i2c.c  --  Arizona I2C bus interface
+ *
+ * Copyright 2012 Wolfson Microelectronics plc
+ *
+ * Author: Mark Brown <broonie@opensource.wolfsonmicro.com>
+ */
+
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/pm_runtime.h>
+#include <linux/regmap.h>
+#include <linux/regulator/consumer.h>
+#include <linux/slab.h>
+#include <linux/of.h>
+
+#include <linux/mfd/arizona/core.h>
+
+#include "arizona.h"
+
+static int arizona_i2c_probe(struct i2c_client *i2c)
+{
+	struct arizona *arizona;
+	const struct regmap_config *regmap_config = NULL;
+	unsigned long type;
+	int ret;
+
+	type = (uintptr_t)i2c_get_match_data(i2c);
+	switch (type) {
+	case WM5102:
+		if (IS_ENABLED(CONFIG_MFD_WM5102))
+			regmap_config = &wm5102_i2c_regmap;
+		break;
+	case WM5110:
+	case WM8280:
+		if (IS_ENABLED(CONFIG_MFD_WM5110))
+			regmap_config = &wm5110_i2c_regmap;
+		break;
+	case WM8997:
+		if (IS_ENABLED(CONFIG_MFD_WM8997))
+			regmap_config = &wm8997_i2c_regmap;
+		break;
+	case WM8998:
+	case WM1814:
+		if (IS_ENABLED(CONFIG_MFD_WM8998))
+			regmap_config = &wm8998_i2c_regmap;
+		break;
+	default:
+		dev_err(&i2c->dev, "Unknown device type %ld\n", type);
+		return -EINVAL;
+	}
+
+	if (!regmap_config) {
+		dev_err(&i2c->dev,
+			"No kernel support for device type %ld\n", type);
+		return -EINVAL;
+	}
+
+	arizona = devm_kzalloc(&i2c->dev, sizeof(*arizona), GFP_KERNEL);
+	if (arizona == NULL)
+		return -ENOMEM;
+
+	arizona->regmap = devm_regmap_init_i2c(i2c, regmap_config);
+	if (IS_ERR(arizona->regmap)) {
+		ret = PTR_ERR(arizona->regmap);
+		dev_err(&i2c->dev, "Failed to allocate register map: %d\n",
+			ret);
+		return ret;
+	}
+
+	arizona->type = type;
+	arizona->dev = &i2c->dev;
+	arizona->irq = i2c->irq;
+
+	return arizona_dev_init(arizona);
+}
+
+static void arizona_i2c_remove(struct i2c_client *i2c)
+{
+	struct arizona *arizona = dev_get_drvdata(&i2c->dev);
+
+	arizona_dev_exit(arizona);
+}
+
+static const struct i2c_device_id arizona_i2c_id[] = {
+	{ "wm5102", WM5102 },
+	{ "wm5110", WM5110 },
+	{ "wm8280", WM8280 },
+	{ "wm8997", WM8997 },
+	{ "wm8998", WM8998 },
+	{ "wm1814", WM1814 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, arizona_i2c_id);
+
+#ifdef CONFIG_OF
+static const struct of_device_id arizona_i2c_of_match[] = {
+	{ .compatible = "wlf,wm5102", .data = (void *)WM5102 },
+	{ .compatible = "wlf,wm5110", .data = (void *)WM5110 },
+	{ .compatible = "wlf,wm8280", .data = (void *)WM8280 },
+	{ .compatible = "wlf,wm8997", .data = (void *)WM8997 },
+	{ .compatible = "wlf,wm8998", .data = (void *)WM8998 },
+	{ .compatible = "wlf,wm1814", .data = (void *)WM1814 },
+	{},
+};
+MODULE_DEVICE_TABLE(of, arizona_i2c_of_match);
+#endif
+
+static struct i2c_driver arizona_i2c_driver = {
+	.driver = {
+		.name	= "arizona",
+		.pm	= pm_ptr(&arizona_pm_ops),
+		.of_match_table	= of_match_ptr(arizona_i2c_of_match),
+	},
+	.probe		= arizona_i2c_probe,
+	.remove		= arizona_i2c_remove,
+	.id_table	= arizona_i2c_id,
+};
+
+module_i2c_driver(arizona_i2c_driver);
+
+MODULE_SOFTDEP("pre: arizona_ldo1");
+MODULE_DESCRIPTION("Arizona I2C bus interface");
+MODULE_AUTHOR("Mark Brown <broonie@opensource.wolfsonmicro.com>");
+MODULE_LICENSE("GPL");