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, 49 insertions, 0 deletions

diff --git a/drivers/hid/hid-accutouch.c b/drivers/hid/hid-accutouch.c
new file mode 100644
index 000000000..bb6c997e9
--- /dev/null
+++ b/drivers/hid/hid-accutouch.c
@@ -0,0 +1,49 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * HID driver for Elo Accutouch touchscreens
+ *
+ * Copyright (c) 2016, Collabora Ltd.
+ * Copyright (c) 2016, General Electric Company
+ *
+ * based on hid-penmount.c
+ *  Copyright (c) 2014 Christian Gmeiner <christian.gmeiner <at> gmail.com>
+ */
+
+/*
+ */
+
+#include <linux/hid.h>
+#include <linux/module.h>
+#include "hid-ids.h"
+
+static int accutouch_input_mapping(struct hid_device *hdev,
+				   struct hid_input *hi,
+				   struct hid_field *field,
+				   struct hid_usage *usage,
+				   unsigned long **bit, int *max)
+{
+	if ((usage->hid & HID_USAGE_PAGE) == HID_UP_BUTTON) {
+		hid_map_usage(hi, usage, bit, max, EV_KEY, BTN_TOUCH);
+		return 1;
+	}
+
+	return 0;
+}
+
+static const struct hid_device_id accutouch_devices[] = {
+	{ HID_USB_DEVICE(USB_VENDOR_ID_ELO, USB_DEVICE_ID_ELO_ACCUTOUCH_2216) },
+	{ }
+};
+MODULE_DEVICE_TABLE(hid, accutouch_devices);
+
+static struct hid_driver accutouch_driver = {
+	.name = "hid-accutouch",
+	.id_table = accutouch_devices,
+	.input_mapping = accutouch_input_mapping,
+};
+
+module_hid_driver(accutouch_driver);
+
+MODULE_AUTHOR("Martyn Welch <martyn.welch@collabora.co.uk");
+MODULE_DESCRIPTION("Elo Accutouch HID TouchScreen driver");
+MODULE_LICENSE("GPL");