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, 97 insertions, 0 deletions

diff --git a/drivers/hid/hid-megaworld.c b/drivers/hid/hid-megaworld.c
new file mode 100644
index 000000000..d5c868974
--- /dev/null
+++ b/drivers/hid/hid-megaworld.c
@@ -0,0 +1,97 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Vibration support for Mega World controllers
+ *
+ * Copyright 2022 Frank Zago
+ *
+ * Derived from hid-zpff.c:
+ *   Copyright (c) 2005, 2006 Anssi Hannula <anssi.hannula@gmail.com>
+ */
+
+#include <linux/hid.h>
+#include <linux/input.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+
+#include "hid-ids.h"
+
+struct mwctrl_device {
+	struct hid_report *report;
+	s32 *weak;
+	s32 *strong;
+};
+
+static int mwctrl_play(struct input_dev *dev, void *data,
+		       struct ff_effect *effect)
+{
+	struct hid_device *hid = input_get_drvdata(dev);
+	struct mwctrl_device *mwctrl = data;
+
+	*mwctrl->strong = effect->u.rumble.strong_magnitude >> 8;
+	*mwctrl->weak = effect->u.rumble.weak_magnitude >> 8;
+
+	hid_hw_request(hid, mwctrl->report, HID_REQ_SET_REPORT);
+
+	return 0;
+}
+
+static int mwctrl_input_configured(struct hid_device *hid, struct hid_input *hidinput)
+{
+	struct mwctrl_device *mwctrl;
+	struct hid_report *report;
+	struct input_dev *dev = hidinput->input;
+	int error;
+	int i;
+
+	if (!list_is_first(&hidinput->list, &hid->inputs))
+		return 0;
+
+	for (i = 0; i < 4; i++) {
+		report = hid_validate_values(hid, HID_OUTPUT_REPORT, 0, i, 1);
+		if (!report)
+			return -ENODEV;
+	}
+
+	mwctrl = kzalloc_obj(struct mwctrl_device);
+	if (!mwctrl)
+		return -ENOMEM;
+
+	mwctrl->report = report;
+	/* Field 0 is always 2, and field 1 is always 0. The original
+	 * windows driver has a 5 bytes command, where the 5th byte is
+	 * a repeat of the 3rd byte, however the device has only 4
+	 * fields. It could be a bug in the driver, or there is a
+	 * different device that needs it.
+	 */
+	report->field[0]->value[0] = 0x02;
+
+	mwctrl->strong = &report->field[2]->value[0];
+	mwctrl->weak = &report->field[3]->value[0];
+
+	set_bit(FF_RUMBLE, dev->ffbit);
+
+	error = input_ff_create_memless(dev, mwctrl, mwctrl_play);
+	if (error) {
+		kfree(mwctrl);
+		return error;
+	}
+
+	return 0;
+}
+
+static const struct hid_device_id mwctrl_devices[] = {
+	{ HID_USB_DEVICE(USB_VENDOR_MEGAWORLD,
+			 USB_DEVICE_ID_MEGAWORLD_GAMEPAD) },
+	{ }
+};
+MODULE_DEVICE_TABLE(hid, mwctrl_devices);
+
+static struct hid_driver mwctrl_driver = {
+	.name = "megaworld",
+	.id_table = mwctrl_devices,
+	.input_configured = mwctrl_input_configured,
+};
+module_hid_driver(mwctrl_driver);
+
+MODULE_DESCRIPTION("Vibration support for Mega World controllers");
+MODULE_LICENSE("GPL");