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, 79 insertions, 0 deletions

diff --git a/drivers/hid/hid-speedlink.c b/drivers/hid/hid-speedlink.c
new file mode 100644
index 000000000..22ee078c4
--- /dev/null
+++ b/drivers/hid/hid-speedlink.c
@@ -0,0 +1,79 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  HID driver for Speedlink Vicious and Divine Cezanne (USB mouse).
+ *  Fixes "jumpy" cursor and removes nonexistent keyboard LEDS from
+ *  the HID descriptor.
+ *
+ *  Copyright (c) 2011, 2013 Stefan Kriwanek <dev@stefankriwanek.de>
+ */
+
+/*
+ */
+
+#include <linux/device.h>
+#include <linux/hid.h>
+#include <linux/module.h>
+
+#include "hid-ids.h"
+
+static const struct hid_device_id speedlink_devices[] = {
+	{ HID_USB_DEVICE(USB_VENDOR_ID_X_TENSIONS, USB_DEVICE_ID_SPEEDLINK_VAD_CEZANNE)},
+	{ }
+};
+
+static int speedlink_input_mapping(struct hid_device *hdev,
+		struct hid_input *hi,
+		struct hid_field *field, struct hid_usage *usage,
+		unsigned long **bit, int *max)
+{
+	/*
+	 * The Cezanne mouse has a second "keyboard" USB endpoint for it is
+	 * able to map keyboard events to the button presses.
+	 * It sends a standard keyboard report descriptor, though, whose
+	 * LEDs we ignore.
+	 */
+	switch (usage->hid & HID_USAGE_PAGE) {
+	case HID_UP_LED:
+		return -1;
+	}
+	return 0;
+}
+
+static int speedlink_event(struct hid_device *hdev, struct hid_field *field,
+		struct hid_usage *usage, __s32 value)
+{
+	/* No other conditions due to usage_table. */
+
+	/* This fixes the "jumpy" cursor occuring due to invalid events sent
+	 * by the device. Some devices only send them with value==+256, others
+	 * don't. However, catching abs(value)>=256 is restrictive enough not
+	 * to interfere with devices that were bug-free (has been tested).
+	 */
+	if (abs(value) >= 256)
+		return 1;
+	/* Drop useless distance 0 events (on button clicks etc.) as well */
+	if (value == 0)
+		return 1;
+
+	return 0;
+}
+
+MODULE_DEVICE_TABLE(hid, speedlink_devices);
+
+static const struct hid_usage_id speedlink_grabbed_usages[] = {
+	{ HID_GD_X, EV_REL, 0 },
+	{ HID_GD_Y, EV_REL, 1 },
+	{ HID_ANY_ID - 1, HID_ANY_ID - 1, HID_ANY_ID - 1}
+};
+
+static struct hid_driver speedlink_driver = {
+	.name = "speedlink",
+	.id_table = speedlink_devices,
+	.usage_table = speedlink_grabbed_usages,
+	.input_mapping = speedlink_input_mapping,
+	.event = speedlink_event,
+};
+module_hid_driver(speedlink_driver);
+
+MODULE_DESCRIPTION("HID driver for Speedlink Vicious and Divine Cezanne (USB mouse)");
+MODULE_LICENSE("GPL");