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, 163 insertions, 0 deletions

diff --git a/drivers/hid/hid-picolcd_leds.c b/drivers/hid/hid-picolcd_leds.c
new file mode 100644
index 000000000..6b505a753
--- /dev/null
+++ b/drivers/hid/hid-picolcd_leds.c
@@ -0,0 +1,163 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/***************************************************************************
+ *   Copyright (C) 2010-2012 by Bruno Prémont <bonbons@linux-vserver.org>  *
+ *                                                                         *
+ *   Based on Logitech G13 driver (v0.4)                                   *
+ *     Copyright (C) 2009 by Rick L. Vinyard, Jr. <rvinyard@cs.nmsu.edu>   *
+ *                                                                         *
+ ***************************************************************************/
+
+#include <linux/hid.h>
+#include <linux/hid-debug.h>
+#include <linux/input.h>
+#include "hid-ids.h"
+
+#include <linux/fb.h>
+#include <linux/vmalloc.h>
+#include <linux/backlight.h>
+#include <linux/lcd.h>
+
+#include <linux/leds.h>
+
+#include <linux/seq_file.h>
+#include <linux/debugfs.h>
+
+#include <linux/completion.h>
+#include <linux/uaccess.h>
+#include <linux/module.h>
+
+#include "hid-picolcd.h"
+
+
+void picolcd_leds_set(struct picolcd_data *data)
+{
+	struct hid_report *report;
+	unsigned long flags;
+
+	if (!data->led[0])
+		return;
+	report = picolcd_out_report(REPORT_LED_STATE, data->hdev);
+	if (!report || report->maxfield != 1 || report->field[0]->report_count != 1)
+		return;
+
+	spin_lock_irqsave(&data->lock, flags);
+	hid_set_field(report->field[0], 0, data->led_state);
+	if (!(data->status & PICOLCD_FAILED))
+		hid_hw_request(data->hdev, report, HID_REQ_SET_REPORT);
+	spin_unlock_irqrestore(&data->lock, flags);
+}
+
+static void picolcd_led_set_brightness(struct led_classdev *led_cdev,
+			enum led_brightness value)
+{
+	struct device *dev;
+	struct hid_device *hdev;
+	struct picolcd_data *data;
+	int i, state = 0;
+
+	dev  = led_cdev->dev->parent;
+	hdev = to_hid_device(dev);
+	data = hid_get_drvdata(hdev);
+	if (!data)
+		return;
+	for (i = 0; i < 8; i++) {
+		if (led_cdev != data->led[i])
+			continue;
+		state = (data->led_state >> i) & 1;
+		if (value == LED_OFF && state) {
+			data->led_state &= ~(1 << i);
+			picolcd_leds_set(data);
+		} else if (value != LED_OFF && !state) {
+			data->led_state |= 1 << i;
+			picolcd_leds_set(data);
+		}
+		break;
+	}
+}
+
+static enum led_brightness picolcd_led_get_brightness(struct led_classdev *led_cdev)
+{
+	struct device *dev;
+	struct hid_device *hdev;
+	struct picolcd_data *data;
+	int i, value = 0;
+
+	dev  = led_cdev->dev->parent;
+	hdev = to_hid_device(dev);
+	data = hid_get_drvdata(hdev);
+	for (i = 0; i < 8; i++)
+		if (led_cdev == data->led[i]) {
+			value = (data->led_state >> i) & 1;
+			break;
+		}
+	return value ? LED_FULL : LED_OFF;
+}
+
+int picolcd_init_leds(struct picolcd_data *data, struct hid_report *report)
+{
+	struct device *dev = &data->hdev->dev;
+	struct led_classdev *led;
+	size_t name_sz = strlen(dev_name(dev)) + 8;
+	char *name;
+	int i, ret = 0;
+
+	if (!report)
+		return -ENODEV;
+	if (report->maxfield != 1 || report->field[0]->report_count != 1 ||
+			report->field[0]->report_size != 8) {
+		dev_err(dev, "unsupported LED_STATE report");
+		return -EINVAL;
+	}
+
+	for (i = 0; i < 8; i++) {
+		led = kzalloc(sizeof(struct led_classdev)+name_sz, GFP_KERNEL);
+		if (!led) {
+			dev_err(dev, "can't allocate memory for LED %d\n", i);
+			ret = -ENOMEM;
+			goto err;
+		}
+		name = (void *)(&led[1]);
+		snprintf(name, name_sz, "%s::GPO%d", dev_name(dev), i);
+		led->name = name;
+		led->brightness = 0;
+		led->max_brightness = 1;
+		led->brightness_get = picolcd_led_get_brightness;
+		led->brightness_set = picolcd_led_set_brightness;
+
+		data->led[i] = led;
+		ret = led_classdev_register(dev, data->led[i]);
+		if (ret) {
+			data->led[i] = NULL;
+			kfree(led);
+			dev_err(dev, "can't register LED %d\n", i);
+			goto err;
+		}
+	}
+	return 0;
+err:
+	for (i = 0; i < 8; i++)
+		if (data->led[i]) {
+			led = data->led[i];
+			data->led[i] = NULL;
+			led_classdev_unregister(led);
+			kfree(led);
+		}
+	return ret;
+}
+
+void picolcd_exit_leds(struct picolcd_data *data)
+{
+	struct led_classdev *led;
+	int i;
+
+	for (i = 0; i < 8; i++) {
+		led = data->led[i];
+		data->led[i] = NULL;
+		if (!led)
+			continue;
+		led_classdev_unregister(led);
+		kfree(led);
+	}
+}
+
+