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, 58 insertions, 0 deletions

diff --git a/drivers/hid/hid-topre.c b/drivers/hid/hid-topre.c
new file mode 100644
index 000000000..ccedf8721
--- /dev/null
+++ b/drivers/hid/hid-topre.c
@@ -0,0 +1,58 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ *  HID driver for Topre REALFORCE Keyboards
+ *
+ *  Copyright (c) 2022 Harry Stern <harry@harrystern.net>
+ *
+ *  Based on the hid-macally driver
+ */
+
+#include <linux/hid.h>
+#include <linux/module.h>
+
+#include "hid-ids.h"
+
+MODULE_AUTHOR("Harry Stern <harry@harrystern.net>");
+MODULE_DESCRIPTION("REALFORCE R2 Keyboard driver");
+MODULE_LICENSE("GPL");
+
+/*
+ * Fix the REALFORCE R2's non-boot interface's report descriptor to match the
+ * events it's actually sending. It claims to send array events but is instead
+ * sending variable events.
+ */
+static const __u8 *topre_report_fixup(struct hid_device *hdev, __u8 *rdesc,
+				      unsigned int *rsize)
+{
+	if (*rsize >= 119 && rdesc[69] == 0x29 && rdesc[70] == 0xe7 &&
+						 rdesc[71] == 0x81 && rdesc[72] == 0x00) {
+		hid_info(hdev,
+			"fixing up Topre REALFORCE keyboard report descriptor\n");
+		rdesc[72] = 0x02;
+	} else if (*rsize >= 106 && rdesc[28] == 0x29 && rdesc[29] == 0xe7 &&
+				    rdesc[30] == 0x81 && rdesc[31] == 0x00) {
+		hid_info(hdev,
+			"fixing up Topre REALFORCE keyboard report descriptor\n");
+		rdesc[31] = 0x02;
+	}
+	return rdesc;
+}
+
+static const struct hid_device_id topre_id_table[] = {
+	{ HID_USB_DEVICE(USB_VENDOR_ID_TOPRE,
+			 USB_DEVICE_ID_TOPRE_REALFORCE_R2_108) },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_TOPRE,
+			 USB_DEVICE_ID_TOPRE_REALFORCE_R2_87) },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_TOPRE,
+			 USB_DEVICE_ID_TOPRE_REALFORCE_R3S_87) },
+	{ }
+};
+MODULE_DEVICE_TABLE(hid, topre_id_table);
+
+static struct hid_driver topre_driver = {
+	.name			= "topre",
+	.id_table		= topre_id_table,
+	.report_fixup		= topre_report_fixup,
+};
+
+module_hid_driver(topre_driver);