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, 156 insertions, 0 deletions

diff --git a/drivers/hid/hid-chicony.c b/drivers/hid/hid-chicony.c
new file mode 100644
index 000000000..5776ec2e7
--- /dev/null
+++ b/drivers/hid/hid-chicony.c
@@ -0,0 +1,156 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  HID driver for some chicony "special" devices
+ *
+ *  Copyright (c) 1999 Andreas Gal
+ *  Copyright (c) 2000-2005 Vojtech Pavlik <vojtech@suse.cz>
+ *  Copyright (c) 2005 Michael Haboustak <mike-@cinci.rr.com> for Concept2, Inc
+ *  Copyright (c) 2006-2007 Jiri Kosina
+ *  Copyright (c) 2007 Paul Walmsley
+ *  Copyright (c) 2008 Jiri Slaby
+ */
+
+/*
+ */
+
+#include <linux/device.h>
+#include <linux/input.h>
+#include <linux/hid.h>
+#include <linux/module.h>
+#include <linux/usb.h>
+
+#include "hid-ids.h"
+
+#define CH_WIRELESS_CTL_REPORT_ID	0x11
+
+static int ch_report_wireless(struct hid_report *report, u8 *data, int size)
+{
+	struct hid_device *hdev = report->device;
+	struct input_dev *input;
+
+	if (report->id != CH_WIRELESS_CTL_REPORT_ID || report->maxfield != 1)
+		return 0;
+
+	input = report->field[0]->hidinput->input;
+	if (!input) {
+		hid_warn(hdev, "can't find wireless radio control's input");
+		return 0;
+	}
+
+	input_report_key(input, KEY_RFKILL, 1);
+	input_sync(input);
+	input_report_key(input, KEY_RFKILL, 0);
+	input_sync(input);
+
+	return 1;
+}
+
+static int ch_raw_event(struct hid_device *hdev,
+		struct hid_report *report, u8 *data, int size)
+{
+	if (report->application == HID_GD_WIRELESS_RADIO_CTLS)
+		return ch_report_wireless(report, data, size);
+
+	return 0;
+}
+
+#define ch_map_key_clear(c)	hid_map_usage_clear(hi, usage, bit, max, \
+					EV_KEY, (c))
+static int ch_input_mapping(struct hid_device *hdev, struct hid_input *hi,
+		struct hid_field *field, struct hid_usage *usage,
+		unsigned long **bit, int *max)
+{
+	if ((usage->hid & HID_USAGE_PAGE) != HID_UP_MSVENDOR)
+		return 0;
+
+	set_bit(EV_REP, hi->input->evbit);
+	switch (usage->hid & HID_USAGE) {
+	case 0xff01: ch_map_key_clear(BTN_1);	break;
+	case 0xff02: ch_map_key_clear(BTN_2);	break;
+	case 0xff03: ch_map_key_clear(BTN_3);	break;
+	case 0xff04: ch_map_key_clear(BTN_4);	break;
+	case 0xff05: ch_map_key_clear(BTN_5);	break;
+	case 0xff06: ch_map_key_clear(BTN_6);	break;
+	case 0xff07: ch_map_key_clear(BTN_7);	break;
+	case 0xff08: ch_map_key_clear(BTN_8);	break;
+	case 0xff09: ch_map_key_clear(BTN_9);	break;
+	case 0xff0a: ch_map_key_clear(BTN_A);	break;
+	case 0xff0b: ch_map_key_clear(BTN_B);	break;
+	case 0x00f1: ch_map_key_clear(KEY_WLAN);	break;
+	case 0x00f2: ch_map_key_clear(KEY_BRIGHTNESSDOWN);	break;
+	case 0x00f3: ch_map_key_clear(KEY_BRIGHTNESSUP);	break;
+	case 0x00f4: ch_map_key_clear(KEY_DISPLAY_OFF);	break;
+	case 0x00f7: ch_map_key_clear(KEY_CAMERA);	break;
+	case 0x00f8: ch_map_key_clear(KEY_PROG1);	break;
+	default:
+		return 0;
+	}
+	return 1;
+}
+
+static const __u8 *ch_switch12_report_fixup(struct hid_device *hdev,
+		__u8 *rdesc, unsigned int *rsize)
+{
+	struct usb_interface *intf = to_usb_interface(hdev->dev.parent);
+	
+	if (intf->cur_altsetting->desc.bInterfaceNumber == 1) {
+		/* Change usage maximum and logical maximum from 0x7fff to
+		 * 0x2fff, so they don't exceed HID_MAX_USAGES */
+		switch (hdev->product) {
+		case USB_DEVICE_ID_CHICONY_ACER_SWITCH12:
+			if (*rsize >= 128 && rdesc[64] == 0xff && rdesc[65] == 0x7f
+					&& rdesc[69] == 0xff && rdesc[70] == 0x7f) {
+				hid_info(hdev, "Fixing up report descriptor\n");
+				rdesc[65] = rdesc[70] = 0x2f;
+			}
+			break;
+		}
+
+	}
+	return rdesc;
+}
+
+static int ch_probe(struct hid_device *hdev, const struct hid_device_id *id)
+{
+	int ret;
+
+	if (!hid_is_usb(hdev))
+		return -EINVAL;
+
+	hdev->quirks |= HID_QUIRK_INPUT_PER_APP;
+	ret = hid_parse(hdev);
+	if (ret) {
+		hid_err(hdev, "Chicony hid parse failed: %d\n", ret);
+		return ret;
+	}
+
+	ret = hid_hw_start(hdev, HID_CONNECT_DEFAULT);
+	if (ret) {
+		hid_err(hdev, "Chicony hw start failed: %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static const struct hid_device_id ch_devices[] = {
+	{ HID_USB_DEVICE(USB_VENDOR_ID_CHICONY, USB_DEVICE_ID_CHICONY_TACTICAL_PAD) },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_CHICONY, USB_DEVICE_ID_CHICONY_WIRELESS2) },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_CHICONY, USB_DEVICE_ID_CHICONY_WIRELESS3) },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_CHICONY, USB_DEVICE_ID_CHICONY_ACER_SWITCH12) },
+	{ }
+};
+MODULE_DEVICE_TABLE(hid, ch_devices);
+
+static struct hid_driver ch_driver = {
+	.name = "chicony",
+	.id_table = ch_devices,
+	.report_fixup = ch_switch12_report_fixup,
+	.input_mapping = ch_input_mapping,
+	.probe = ch_probe,
+	.raw_event = ch_raw_event,
+};
+module_hid_driver(ch_driver);
+
+MODULE_DESCRIPTION("HID driver for some chicony \"special\" devices");
+MODULE_LICENSE("GPL");