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, 109 insertions, 0 deletions

diff --git a/drivers/gpio/gpiolib-legacy.c b/drivers/gpio/gpiolib-legacy.c
new file mode 100644
index 000000000..ef3f2ef30
--- /dev/null
+++ b/drivers/gpio/gpiolib-legacy.c
@@ -0,0 +1,109 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/bitops.h>
+#include <linux/device.h>
+#include <linux/errno.h>
+#include <linux/export.h>
+#include <linux/gfp.h>
+
+#include <linux/gpio/consumer.h>
+#include <linux/gpio/driver.h>
+
+#include <linux/gpio.h>
+
+#include "gpiolib.h"
+
+/*
+ * **DEPRECATED** This function is deprecated and must not be used in new code.
+ */
+void gpio_free(unsigned gpio)
+{
+	gpiod_free(gpio_to_desc(gpio));
+}
+EXPORT_SYMBOL_GPL(gpio_free);
+
+/**
+ * gpio_request_one - request a single GPIO with initial configuration
+ * @gpio:	the GPIO number
+ * @flags:	GPIO configuration as specified by GPIOF_*
+ * @label:	a literal description string of this GPIO
+ *
+ * **DEPRECATED** This function is deprecated and must not be used in new code.
+ *
+ * Returns:
+ * 0 on success, or negative errno on failure.
+ */
+int gpio_request_one(unsigned gpio, unsigned long flags, const char *label)
+{
+	int err;
+
+	err = gpio_request(gpio, label);
+	if (err)
+		return err;
+
+	if (flags & GPIOF_IN)
+		err = gpio_direction_input(gpio);
+	else
+		err = gpio_direction_output(gpio, !!(flags & GPIOF_OUT_INIT_HIGH));
+
+	if (err)
+		gpio_free(gpio);
+
+	return err;
+}
+EXPORT_SYMBOL_GPL(gpio_request_one);
+
+/*
+ * **DEPRECATED** This function is deprecated and must not be used in new code.
+ */
+int gpio_request(unsigned gpio, const char *label)
+{
+	struct gpio_desc *desc;
+
+	/* Compatibility: assume unavailable "valid" GPIOs will appear later */
+	desc = gpio_to_desc(gpio);
+	if (!desc)
+		return -EPROBE_DEFER;
+
+	return gpiod_request(desc, label);
+}
+EXPORT_SYMBOL_GPL(gpio_request);
+
+static void devm_gpio_release(void *gpio)
+{
+	gpio_free((unsigned)(unsigned long)gpio);
+}
+
+/**
+ * devm_gpio_request_one - request a single GPIO with initial setup
+ * @dev: device to request for
+ * @gpio: the GPIO number
+ * @flags: GPIO configuration as specified by GPIOF_*
+ * @label: a literal description string of this GPIO
+ *
+ * **DEPRECATED** This function is deprecated and must not be used in new code.
+ *
+ * Returns:
+ * 0 on success, or negative errno on failure.
+ */
+int devm_gpio_request_one(struct device *dev, unsigned gpio,
+			  unsigned long flags, const char *label)
+{
+	int rc;
+
+	rc = gpio_request(gpio, label);
+	if (rc)
+		return rc;
+
+	if (flags & GPIOF_IN)
+		rc = gpio_direction_input(gpio);
+	else
+		rc = gpio_direction_output(gpio, !!(flags & GPIOF_OUT_INIT_HIGH));
+
+	if (rc) {
+		gpio_free(gpio);
+		return rc;
+	}
+
+	return devm_add_action_or_reset(dev, devm_gpio_release, (void *)(unsigned long)gpio);
+}
+EXPORT_SYMBOL_GPL(devm_gpio_request_one);