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, 155 insertions, 0 deletions

diff --git a/drivers/hid/hid-betopff.c b/drivers/hid/hid-betopff.c
new file mode 100644
index 000000000..f802046a6
--- /dev/null
+++ b/drivers/hid/hid-betopff.c
@@ -0,0 +1,155 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  Force feedback support for Betop based devices
+ *
+ *  The devices are distributed under various names and the same USB device ID
+ *  can be used in both adapters and actual game controllers.
+ *
+ *  0x11c2:0x2208 "BTP2185 BFM mode Joystick"
+ *   - tested with BTP2185 BFM Mode.
+ *
+ *  0x11C0:0x5506 "BTP2185 PC mode Joystick"
+ *   - tested with BTP2185 PC Mode.
+ *
+ *  0x8380:0x1850 "BTP2185 V2 PC mode USB Gamepad"
+ *   - tested with BTP2185 PC Mode with another version.
+ *
+ *  0x20bc:0x5500 "BTP2185 V2 BFM mode Joystick"
+ *   - tested with BTP2171s.
+ *  Copyright (c) 2014 Huang Bo <huangbobupt@163.com>
+ */
+
+/*
+ */
+
+
+#include <linux/input.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/hid.h>
+
+#include "hid-ids.h"
+
+struct betopff_device {
+	struct hid_report *report;
+};
+
+static int hid_betopff_play(struct input_dev *dev, void *data,
+			 struct ff_effect *effect)
+{
+	struct hid_device *hid = input_get_drvdata(dev);
+	struct betopff_device *betopff = data;
+	__u16 left, right;
+
+	left = effect->u.rumble.strong_magnitude;
+	right = effect->u.rumble.weak_magnitude;
+
+	betopff->report->field[2]->value[0] = left / 256;
+	betopff->report->field[3]->value[0] = right / 256;
+
+	hid_hw_request(hid, betopff->report, HID_REQ_SET_REPORT);
+
+	return 0;
+}
+
+static int betop_input_configured(struct hid_device *hid, struct hid_input *hidinput)
+{
+	struct betopff_device *betopff;
+	struct hid_report *report;
+	struct list_head *report_list =
+			&hid->report_enum[HID_OUTPUT_REPORT].report_list;
+	struct input_dev *dev = hidinput->input;
+	int error;
+	int i, j;
+
+	if (!list_is_first(&hidinput->list, &hid->inputs))
+		return 0;
+
+	report = list_first_entry_or_null(report_list, struct hid_report, list);
+	if (!report) {
+		hid_err(hid, "no output reports found\n");
+		return -ENODEV;
+	}
+	/*
+	 * Actually there are 4 fields for 4 Bytes as below:
+	 * -----------------------------------------
+	 * Byte0  Byte1  Byte2	  Byte3
+	 * 0x00   0x00   left_motor right_motor
+	 * -----------------------------------------
+	 * Do init them with default value.
+	 */
+	if (report->maxfield < 4) {
+		hid_err(hid, "not enough fields in the report: %d\n",
+				report->maxfield);
+		return -ENODEV;
+	}
+	for (i = 0; i < report->maxfield; i++) {
+		if (report->field[i]->report_count < 1) {
+			hid_err(hid, "no values in the field\n");
+			return -ENODEV;
+		}
+		for (j = 0; j < report->field[i]->report_count; j++) {
+			report->field[i]->value[j] = 0x00;
+		}
+	}
+
+	betopff = kzalloc_obj(*betopff);
+	if (!betopff)
+		return -ENOMEM;
+
+	betopff->report = report;
+	set_bit(FF_RUMBLE, dev->ffbit);
+
+	error = input_ff_create_memless(dev, betopff, hid_betopff_play);
+	if (error) {
+		kfree(betopff);
+		return error;
+	}
+
+	hid_hw_request(hid, betopff->report, HID_REQ_SET_REPORT);
+
+	hid_info(hid, "Force feedback for betop devices by huangbo <huangbobupt@163.com>\n");
+
+	return 0;
+}
+
+static int betop_probe(struct hid_device *hdev, const struct hid_device_id *id)
+{
+	int ret;
+
+	if (id->driver_data)
+		hdev->quirks |= HID_QUIRK_MULTI_INPUT;
+
+	ret = hid_parse(hdev);
+	if (ret) {
+		hid_err(hdev, "parse failed\n");
+		return ret;
+	}
+
+	ret = hid_hw_start(hdev, HID_CONNECT_DEFAULT);
+	if (ret) {
+		hid_err(hdev, "hw start failed\n");
+		return ret;
+	}
+	return 0;
+}
+
+static const struct hid_device_id betop_devices[] = {
+	{ HID_USB_DEVICE(USB_VENDOR_ID_BETOP_2185BFM, 0x2208) },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_BETOP_2185PC, 0x5506) },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_BETOP_2185V2PC, 0x1850) },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_BETOP_2185V2BFM, 0x5500) },
+	{ }
+};
+MODULE_DEVICE_TABLE(hid, betop_devices);
+
+static struct hid_driver betop_driver = {
+	.name = "betop",
+	.id_table = betop_devices,
+	.probe = betop_probe,
+	.input_configured = betop_input_configured,
+};
+module_hid_driver(betop_driver);
+
+MODULE_DESCRIPTION("Force feedback support for Betop based devices");
+MODULE_LICENSE("GPL");