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, 209 insertions, 0 deletions

diff --git a/drivers/hid/hid-zydacron.c b/drivers/hid/hid-zydacron.c
new file mode 100644
index 000000000..1aae80f84
--- /dev/null
+++ b/drivers/hid/hid-zydacron.c
@@ -0,0 +1,209 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+*  HID driver for zydacron remote control
+*
+*  Copyright (c) 2010 Don Prince <dhprince.devel@yahoo.co.uk>
+*/
+
+/*
+*/
+
+#include <linux/device.h>
+#include <linux/hid.h>
+#include <linux/module.h>
+
+#include "hid-ids.h"
+
+struct zc_device {
+	struct input_dev	*input_ep81;
+	unsigned short		last_key[4];
+};
+
+
+/*
+* Zydacron remote control has an invalid HID report descriptor,
+* that needs fixing before we can parse it.
+*/
+static const __u8 *zc_report_fixup(struct hid_device *hdev, __u8 *rdesc,
+	unsigned int *rsize)
+{
+	if (*rsize >= 253 &&
+		rdesc[0x96] == 0xbc && rdesc[0x97] == 0xff &&
+		rdesc[0xca] == 0xbc && rdesc[0xcb] == 0xff &&
+		rdesc[0xe1] == 0xbc && rdesc[0xe2] == 0xff) {
+			hid_info(hdev,
+				"fixing up zydacron remote control report descriptor\n");
+			rdesc[0x96] = rdesc[0xca] = rdesc[0xe1] = 0x0c;
+			rdesc[0x97] = rdesc[0xcb] = rdesc[0xe2] = 0x00;
+		}
+	return rdesc;
+}
+
+#define zc_map_key_clear(c) \
+	hid_map_usage_clear(hi, usage, bit, max, EV_KEY, (c))
+
+static int zc_input_mapping(struct hid_device *hdev, struct hid_input *hi,
+	struct hid_field *field, struct hid_usage *usage,
+	unsigned long **bit, int *max)
+{
+	int i;
+	struct zc_device *zc = hid_get_drvdata(hdev);
+	zc->input_ep81 = hi->input;
+
+	if ((usage->hid & HID_USAGE_PAGE) != HID_UP_CONSUMER)
+		return 0;
+
+	dbg_hid("zynacron input mapping event [0x%x]\n",
+		usage->hid & HID_USAGE);
+
+	switch (usage->hid & HID_USAGE) {
+	/* report 2 */
+	case 0x10:
+		zc_map_key_clear(KEY_MODE);
+		break;
+	case 0x30:
+		zc_map_key_clear(KEY_SCREEN);
+		break;
+	case 0x70:
+		zc_map_key_clear(KEY_INFO);
+		break;
+	/* report 3 */
+	case 0x04:
+		zc_map_key_clear(KEY_RADIO);
+		break;
+	/* report 4 */
+	case 0x0d:
+		zc_map_key_clear(KEY_PVR);
+		break;
+	case 0x25:
+		zc_map_key_clear(KEY_TV);
+		break;
+	case 0x47:
+		zc_map_key_clear(KEY_AUDIO);
+		break;
+	case 0x49:
+		zc_map_key_clear(KEY_AUX);
+		break;
+	case 0x4a:
+		zc_map_key_clear(KEY_VIDEO);
+		break;
+	case 0x48:
+		zc_map_key_clear(KEY_DVD);
+		break;
+	case 0x24:
+		zc_map_key_clear(KEY_MENU);
+		break;
+	case 0x32:
+		zc_map_key_clear(KEY_TEXT);
+		break;
+	default:
+		return 0;
+	}
+
+	for (i = 0; i < 4; i++)
+		zc->last_key[i] = 0;
+
+	return 1;
+}
+
+static int zc_raw_event(struct hid_device *hdev, struct hid_report *report,
+	 u8 *data, int size)
+{
+	struct zc_device *zc = hid_get_drvdata(hdev);
+	int ret = 0;
+	unsigned key;
+	unsigned short index;
+
+	if (report->id == data[0] && (hdev->claimed & HID_CLAIMED_INPUT)) {
+
+		/* break keys */
+		for (index = 0; index < 4; index++) {
+			key = zc->last_key[index];
+			if (key) {
+				input_event(zc->input_ep81, EV_KEY, key, 0);
+				zc->last_key[index] = 0;
+			}
+		}
+
+		key = 0;
+		switch (report->id) {
+		case 0x02:
+		case 0x03:
+			switch (data[1]) {
+			case 0x10:
+				key = KEY_MODE;
+				index = 0;
+				break;
+			case 0x30:
+				key = KEY_SCREEN;
+				index = 1;
+				break;
+			case 0x70:
+				key = KEY_INFO;
+				index = 2;
+				break;
+			case 0x04:
+				key = KEY_RADIO;
+				index = 3;
+				break;
+			}
+
+			if (key) {
+				input_event(zc->input_ep81, EV_KEY, key, 1);
+				zc->last_key[index] = key;
+			}
+
+			ret = 1;
+			break;
+		}
+	}
+
+	return ret;
+}
+
+static int zc_probe(struct hid_device *hdev, const struct hid_device_id *id)
+{
+	int ret;
+	struct zc_device *zc;
+
+	zc = devm_kzalloc(&hdev->dev, sizeof(*zc), GFP_KERNEL);
+	if (zc == NULL) {
+		hid_err(hdev, "can't alloc descriptor\n");
+		return -ENOMEM;
+	}
+
+	hid_set_drvdata(hdev, zc);
+
+	ret = hid_parse(hdev);
+	if (ret) {
+		hid_err(hdev, "parse failed\n");
+		return ret;
+	}
+
+	ret = hid_hw_start(hdev, HID_CONNECT_DEFAULT);
+	if (ret) {
+		hid_err(hdev, "hw start failed\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+static const struct hid_device_id zc_devices[] = {
+	{ HID_USB_DEVICE(USB_VENDOR_ID_ZYDACRON, USB_DEVICE_ID_ZYDACRON_REMOTE_CONTROL) },
+	{ }
+};
+MODULE_DEVICE_TABLE(hid, zc_devices);
+
+static struct hid_driver zc_driver = {
+	.name = "zydacron",
+	.id_table = zc_devices,
+	.report_fixup = zc_report_fixup,
+	.input_mapping = zc_input_mapping,
+	.raw_event = zc_raw_event,
+	.probe = zc_probe,
+};
+module_hid_driver(zc_driver);
+
+MODULE_DESCRIPTION("HID driver for zydacron remote control");
+MODULE_LICENSE("GPL");