bpf: mark a NULL kfunc argument precisegrafted

check_kfunc_arg() allows bpf_register_is_null() for nullable arguments
w/o marking the underlying scalar register precise. Hence a checkpoint
created on such a path would prune against arbitrary scalar value.

Fixes: 3bda08b63670 ("bpf: Allow NULL buffers in bpf_dynptr_slice(_rw)")
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260904-register-is-null-precise-fixes-v1-5-0f5a360ff15d@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 75 insertions, 0 deletions

diff --git a/drivers/hid/hid-rakk.c b/drivers/hid/hid-rakk.c
new file mode 100644
index 000000000..1140058a7
--- /dev/null
+++ b/drivers/hid/hid-rakk.c
@@ -0,0 +1,75 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  HID driver for Rakk devices
+ *
+ *  Copyright (c) 2026 Karl Cayme
+ *
+ *  The Rakk Dasig X gaming mouse has a faulty HID report descriptor that
+ *  declares USAGE_MAXIMUM = 3 (buttons 1-3) while actually sending 5 button
+ *  bits (REPORT_COUNT = 5). This causes the kernel to ignore side buttons
+ *  (buttons 4 and 5). This driver fixes the descriptor so all 5 buttons
+ *  are properly recognized across 3 modes (wired, dongle, and Bluetooth).
+ */
+
+#include <linux/device.h>
+#include <linux/hid.h>
+#include <linux/module.h>
+#include "hid-ids.h"
+
+/*
+ * The faulty byte is at offset 17 in the report descriptor for all three
+ * connection modes (USB direct, wireless dongle, and Bluetooth).
+ *
+ * Bytes 16-17 are: 0x29 0x03 (USAGE_MAXIMUM = 3)
+ * The fix changes byte 17 to 0x05 (USAGE_MAXIMUM = 5).
+ *
+ * Original descriptor bytes 0-17:
+ *   05 01 09 02 a1 01 85 01 09 01 a1 00 05 09 19 01 29 03
+ *                                                       ^^
+ *   Should be 0x05 to declare 5 buttons instead of 3.
+ */
+#define RAKK_RDESC_USAGE_MAX_OFFSET	17
+#define RAKK_RDESC_USAGE_MAX_ORIG	0x03
+#define RAKK_RDESC_USAGE_MAX_FIXED	0x05
+#define RAKK_RDESC_USB_SIZE		193
+#define RAKK_RDESC_DONGLE_SIZE		150
+#define RAKK_RDESC_BT_SIZE		89
+
+static const __u8 *rakk_report_fixup(struct hid_device *hdev, __u8 *rdesc,
+				     unsigned int *rsize)
+{
+	if (((*rsize == RAKK_RDESC_USB_SIZE &&
+	      hdev->product == USB_DEVICE_ID_TELINK_RAKK_DASIG_X) ||
+	     (*rsize == RAKK_RDESC_DONGLE_SIZE &&
+	      hdev->product == USB_DEVICE_ID_TELINK_RAKK_DASIG_X_DONGLE) ||
+	     (*rsize == RAKK_RDESC_BT_SIZE &&
+	      hdev->product == USB_DEVICE_ID_TELINK_RAKK_DASIG_X_BT)) &&
+	    rdesc[RAKK_RDESC_USAGE_MAX_OFFSET] == RAKK_RDESC_USAGE_MAX_ORIG) {
+		hid_info(hdev, "fixing Rakk Dasig X button count (3 -> 5)\n");
+		rdesc[RAKK_RDESC_USAGE_MAX_OFFSET] = RAKK_RDESC_USAGE_MAX_FIXED;
+	}
+
+	return rdesc;
+}
+
+static const struct hid_device_id rakk_devices[] = {
+	{ HID_USB_DEVICE(USB_VENDOR_ID_TELINK,
+			 USB_DEVICE_ID_TELINK_RAKK_DASIG_X) },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_TELINK,
+			 USB_DEVICE_ID_TELINK_RAKK_DASIG_X_DONGLE) },
+	{ HID_BLUETOOTH_DEVICE(USB_VENDOR_ID_TELINK,
+			       USB_DEVICE_ID_TELINK_RAKK_DASIG_X_BT) },
+	{ }
+};
+MODULE_DEVICE_TABLE(hid, rakk_devices);
+
+static struct hid_driver rakk_driver = {
+	.name = "rakk",
+	.id_table = rakk_devices,
+	.report_fixup = rakk_report_fixup,
+};
+module_hid_driver(rakk_driver);
+
+MODULE_DESCRIPTION("HID driver for Rakk Dasig X mouse - fix side button support");
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Karl Cayme");