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, 63 insertions, 0 deletions

diff --git a/drivers/hid/hid-redragon.c b/drivers/hid/hid-redragon.c
new file mode 100644
index 000000000..20d28ed75
--- /dev/null
+++ b/drivers/hid/hid-redragon.c
@@ -0,0 +1,63 @@
+/*
+ *  HID driver for Redragon keyboards
+ *
+ *  Copyright (c) 2017 Robert Munteanu
+ *  SPDX-License-Identifier: GPL-2.0+
+ */
+
+/*
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ */
+
+#include <linux/device.h>
+#include <linux/hid.h>
+#include <linux/module.h>
+
+#include "hid-ids.h"
+
+
+/*
+ * The Redragon Asura keyboard sends an incorrect HID descriptor.
+ * At byte 100 it contains
+ *
+ *   0x81, 0x00
+ *
+ * which is Input (Data, Arr, Abs), but it should be
+ *
+ *   0x81, 0x02
+ *
+ * which is Input (Data, Var, Abs), which is consistent with the way
+ * key codes are generated.
+ */
+
+static const __u8 *redragon_report_fixup(struct hid_device *hdev, __u8 *rdesc,
+	unsigned int *rsize)
+{
+	if (*rsize >= 102 && rdesc[100] == 0x81 && rdesc[101] == 0x00) {
+		dev_info(&hdev->dev, "Fixing Redragon ASURA report descriptor.\n");
+		rdesc[101] = 0x02;
+	}
+
+	return rdesc;
+}
+
+static const struct hid_device_id redragon_devices[] = {
+	{HID_USB_DEVICE(USB_VENDOR_ID_JESS, USB_DEVICE_ID_REDRAGON_ASURA)},
+	{}
+};
+
+MODULE_DEVICE_TABLE(hid, redragon_devices);
+
+static struct hid_driver redragon_driver = {
+	.name = "redragon",
+	.id_table = redragon_devices,
+	.report_fixup = redragon_report_fixup
+};
+
+module_hid_driver(redragon_driver);
+
+MODULE_DESCRIPTION("HID driver for Redragon keyboards");
+MODULE_LICENSE("GPL");