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, 94 insertions, 0 deletions

diff --git a/drivers/hid/hid-xiaomi.c b/drivers/hid/hid-xiaomi.c
new file mode 100644
index 000000000..ef6598550
--- /dev/null
+++ b/drivers/hid/hid-xiaomi.c
@@ -0,0 +1,94 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * HID driver for Xiaomi Mi Dual Mode Wireless Mouse Silent Edition
+ *
+ * Copyright (c) 2021 Ilya Skriblovsky
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/hid.h>
+
+#include "hid-ids.h"
+
+/* Fixed Mi Silent Mouse report descriptor */
+/* Button's Usage Maximum changed from 3 to 5 to make side buttons work */
+#define MI_SILENT_MOUSE_ORIG_RDESC_LENGTH   87
+static const __u8 mi_silent_mouse_rdesc_fixed[] = {
+	0x05, 0x01,         /*  Usage Page (Desktop),               */
+	0x09, 0x02,         /*  Usage (Mouse),                      */
+	0xA1, 0x01,         /*  Collection (Application),           */
+	0x85, 0x03,         /*      Report ID (3),                  */
+	0x09, 0x01,         /*      Usage (Pointer),                */
+	0xA1, 0x00,         /*      Collection (Physical),          */
+	0x05, 0x09,         /*          Usage Page (Button),        */
+	0x19, 0x01,         /*          Usage Minimum (01h),        */
+	0x29, 0x05, /* X */ /*          Usage Maximum (05h),        */
+	0x15, 0x00,         /*          Logical Minimum (0),        */
+	0x25, 0x01,         /*          Logical Maximum (1),        */
+	0x75, 0x01,         /*          Report Size (1),            */
+	0x95, 0x05,         /*          Report Count (5),           */
+	0x81, 0x02,         /*          Input (Variable),           */
+	0x75, 0x03,         /*          Report Size (3),            */
+	0x95, 0x01,         /*          Report Count (1),           */
+	0x81, 0x01,         /*          Input (Constant),           */
+	0x05, 0x01,         /*          Usage Page (Desktop),       */
+	0x09, 0x30,         /*          Usage (X),                  */
+	0x09, 0x31,         /*          Usage (Y),                  */
+	0x15, 0x81,         /*          Logical Minimum (-127),     */
+	0x25, 0x7F,         /*          Logical Maximum (127),      */
+	0x75, 0x08,         /*          Report Size (8),            */
+	0x95, 0x02,         /*          Report Count (2),           */
+	0x81, 0x06,         /*          Input (Variable, Relative), */
+	0x09, 0x38,         /*          Usage (Wheel),              */
+	0x15, 0x81,         /*          Logical Minimum (-127),     */
+	0x25, 0x7F,         /*          Logical Maximum (127),      */
+	0x75, 0x08,         /*          Report Size (8),            */
+	0x95, 0x01,         /*          Report Count (1),           */
+	0x81, 0x06,         /*          Input (Variable, Relative), */
+	0xC0,               /*      End Collection,                 */
+	0xC0,               /*  End Collection,                     */
+	0x06, 0x01, 0xFF,   /*  Usage Page (FF01h),                 */
+	0x09, 0x01,         /*  Usage (01h),                        */
+	0xA1, 0x01,         /*  Collection (Application),           */
+	0x85, 0x05,         /*      Report ID (5),                  */
+	0x09, 0x05,         /*      Usage (05h),                    */
+	0x15, 0x00,         /*      Logical Minimum (0),            */
+	0x26, 0xFF, 0x00,   /*      Logical Maximum (255),          */
+	0x75, 0x08,         /*      Report Size (8),                */
+	0x95, 0x04,         /*      Report Count (4),               */
+	0xB1, 0x02,         /*      Feature (Variable),             */
+	0xC0                /*  End Collection                      */
+};
+
+static const __u8 *xiaomi_report_fixup(struct hid_device *hdev, __u8 *rdesc,
+				       unsigned int *rsize)
+{
+	switch (hdev->product) {
+	case USB_DEVICE_ID_MI_SILENT_MOUSE:
+		if (*rsize == MI_SILENT_MOUSE_ORIG_RDESC_LENGTH) {
+			hid_info(hdev, "fixing up Mi Silent Mouse report descriptor\n");
+			*rsize = sizeof(mi_silent_mouse_rdesc_fixed);
+			return mi_silent_mouse_rdesc_fixed;
+		}
+		break;
+	}
+	return rdesc;
+}
+
+static const struct hid_device_id xiaomi_devices[] = {
+	{ HID_BLUETOOTH_DEVICE(USB_VENDOR_ID_XIAOMI, USB_DEVICE_ID_MI_SILENT_MOUSE) },
+	{ }
+};
+MODULE_DEVICE_TABLE(hid, xiaomi_devices);
+
+static struct hid_driver xiaomi_driver = {
+	.name = "xiaomi",
+	.id_table = xiaomi_devices,
+	.report_fixup = xiaomi_report_fixup,
+};
+module_hid_driver(xiaomi_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Ilya Skriblovsky <IlyaSkriblovsky@gmail.com>");
+MODULE_DESCRIPTION("Fixing side buttons of Xiaomi Mi Silent Mouse");