x86/kprobes: Fix crash when probing CS CALL instructionsgrafted

When using eBPF to probe CS CALL instructions within a function,
a crash can be triggered.

The eBPF tool probes offset 257 of the __hrtimer_run_queues()
function:

<__hrtimer_run_queues+249>:  nopl   0x0(%rax,%rax,1)
<__hrtimer_run_queues+254>:  mov    %r14,%rdi
<__hrtimer_run_queues+257>:  cs call <__x86_indirect_thunk_r12>
<__hrtimer_run_queues+263>:  mov    %eax,%r12d
<__hrtimer_run_queues+266>:  xchg   %ax,%ax
<__hrtimer_run_queues+268>:  mov    %r13,%rdi

Which triggers this crash:

  BUG: unable to handle page fault for address: 00000000000f41c9
  #PF: supervisor write access in kernel mode
  #PF: error_code(0x0002) - not-present page
  PGD 0 P4D 0
  Oops: 0002 [#1] SMP NOPTI
  CPU: 1 PID: 0 Comm: swapper/1 Kdump: loaded Tainted: P
  RIP: 0010:__hrtimer_run_queues+0x106/0x230

Note that __hrtimer_run_queues+0x106 is __hrtimer_run_queues+262, which is
at the 6th byte of the above CS CALL instruction. Since the CS CALL
instruction occupies 6 bytes, the exception occurred in the middle of that
call instruction.

The root cause is that when using eBPF tools to probe in the middle of a
function, a kprobe with INT3 is used as the underlying implementation.

During single-step emulation of the original CALL instruction,
int3_emulate_call() assumes that the probed CALL instruction is 5 bytes
long. However, the actual CS-prefixed CALL instruction occupies 6 bytes,
so it constructs an incorrect exception return address. When the CPU
returns from the kprobe handler, the next instruction to be executed is at
the address of the last byte of that CS CALL instruction. Coincidentally,
starting from that address, the CPU fetches and decodes a completely
different instruction, which ultimately triggers a kernel crash.

Fix the issue by using the actual instruction length obtained from
the instruction decoder when constructing the exception return
address, rather than relying on the hardcoded CALL_INSN_SIZE macro.

[ mingo: Refined the changelog ]

Fixes: 6256e668b7af ("x86/kprobes: Use int3 instead of debug trap for single-step")
Suggested-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Jinke Han <jinkehan@didiglobal.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Yafang Shao <laoar.shao@gmail.com>
Acked-by: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://patch.msgid.link/20260908073742.GA10517@didi-ThinkCentre-M920t-N000

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");