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, 208 insertions, 0 deletions

diff --git a/drivers/hid/hid-saitek.c b/drivers/hid/hid-saitek.c
new file mode 100644
index 000000000..6fe7c087c
--- /dev/null
+++ b/drivers/hid/hid-saitek.c
@@ -0,0 +1,208 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  HID driver for Saitek devices.
+ *
+ *  PS1000 (USB gamepad):
+ *  Fixes the HID report descriptor by removing a non-existent axis and
+ *  clearing the constant bit on the input reports for buttons and d-pad.
+ *  (This module is based on "hid-ortek".)
+ *  Copyright (c) 2012 Andreas Hübner
+ *
+ *  R.A.T.7, R.A.T.9, M.M.O.7 (USB gaming mice):
+ *  Fixes the mode button which cycles through three constantly pressed
+ *  buttons. All three press events are mapped to one button and the
+ *  missing release event is generated immediately.
+ */
+
+/*
+ */
+
+#include <linux/device.h>
+#include <linux/hid.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+
+#include "hid-ids.h"
+
+#define SAITEK_FIX_PS1000	0x0001
+#define SAITEK_RELEASE_MODE_RAT7	0x0002
+#define SAITEK_RELEASE_MODE_MMO7	0x0004
+
+struct saitek_sc {
+	unsigned long quirks;
+	int mode;
+};
+
+static int saitek_probe(struct hid_device *hdev,
+		const struct hid_device_id *id)
+{
+	unsigned long quirks = id->driver_data;
+	struct saitek_sc *ssc;
+	int ret;
+
+	ssc = devm_kzalloc(&hdev->dev, sizeof(*ssc), GFP_KERNEL);
+	if (ssc == NULL) {
+		hid_err(hdev, "can't alloc saitek descriptor\n");
+		return -ENOMEM;
+	}
+
+	ssc->quirks = quirks;
+	ssc->mode = -1;
+
+	hid_set_drvdata(hdev, ssc);
+
+	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 __u8 *saitek_report_fixup(struct hid_device *hdev, __u8 *rdesc,
+		unsigned int *rsize)
+{
+	struct saitek_sc *ssc = hid_get_drvdata(hdev);
+
+	if ((ssc->quirks & SAITEK_FIX_PS1000) && *rsize == 137 &&
+			rdesc[20] == 0x09 && rdesc[21] == 0x33 &&
+			rdesc[94] == 0x81 && rdesc[95] == 0x03 &&
+			rdesc[110] == 0x81 && rdesc[111] == 0x03) {
+
+		hid_info(hdev, "Fixing up Saitek PS1000 report descriptor\n");
+
+		/* convert spurious axis to a "noop" Logical Minimum (0) */
+		rdesc[20] = 0x15;
+		rdesc[21] = 0x00;
+
+		/* clear constant bit on buttons and d-pad */
+		rdesc[95] = 0x02;
+		rdesc[111] = 0x02;
+
+	}
+	return rdesc;
+}
+
+static int saitek_raw_event(struct hid_device *hdev,
+		struct hid_report *report, u8 *raw_data, int size)
+{
+	struct saitek_sc *ssc = hid_get_drvdata(hdev);
+
+	if (ssc->quirks & SAITEK_RELEASE_MODE_RAT7 && size == 7) {
+		/* R.A.T.7 uses bits 13, 14, 15 for the mode */
+		int mode = -1;
+		if (raw_data[1] & 0x01)
+			mode = 0;
+		else if (raw_data[1] & 0x02)
+			mode = 1;
+		else if (raw_data[1] & 0x04)
+			mode = 2;
+
+		/* clear mode bits */
+		raw_data[1] &= ~0x07;
+
+		if (mode != ssc->mode) {
+			hid_dbg(hdev, "entered mode %d\n", mode);
+			if (ssc->mode != -1) {
+				/* use bit 13 as the mode button */
+				raw_data[1] |= 0x04;
+			}
+			ssc->mode = mode;
+		}
+	} else if (ssc->quirks & SAITEK_RELEASE_MODE_MMO7 && size == 8) {
+
+		/* M.M.O.7 uses bits 8, 22, 23 for the mode */
+		int mode = -1;
+		if (raw_data[1] & 0x80)
+			mode = 0;
+		else if (raw_data[2] & 0x01)
+			mode = 1;
+		else if (raw_data[2] & 0x02)
+			mode = 2;
+
+		/* clear mode bits */
+		raw_data[1] &= ~0x80;
+		raw_data[2] &= ~0x03;
+
+		if (mode != ssc->mode) {
+			hid_dbg(hdev, "entered mode %d\n", mode);
+			if (ssc->mode != -1) {
+				/* use bit 8 as the mode button, bits 22
+				 * and 23 do not represent buttons
+				 * according to the HID report descriptor
+				 */
+				raw_data[1] |= 0x80;
+			}
+			ssc->mode = mode;
+		}
+	}
+
+	return 0;
+}
+
+static int saitek_event(struct hid_device *hdev, struct hid_field *field,
+		struct hid_usage *usage, __s32 value)
+{
+	struct saitek_sc *ssc = hid_get_drvdata(hdev);
+	struct input_dev *input = field->hidinput->input;
+
+	if (usage->type == EV_KEY && value &&
+			(((ssc->quirks & SAITEK_RELEASE_MODE_RAT7) &&
+			  usage->code - BTN_MOUSE == 10) ||
+			((ssc->quirks & SAITEK_RELEASE_MODE_MMO7) &&
+			 usage->code - BTN_MOUSE == 15))) {
+
+		input_report_key(input, usage->code, 1);
+
+		/* report missing release event */
+		input_report_key(input, usage->code, 0);
+
+		return 1;
+	}
+
+	return 0;
+}
+
+static const struct hid_device_id saitek_devices[] = {
+	{ HID_USB_DEVICE(USB_VENDOR_ID_SAITEK, USB_DEVICE_ID_SAITEK_PS1000),
+		.driver_data = SAITEK_FIX_PS1000 },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_MADCATZ, USB_DEVICE_ID_MADCATZ_RAT5),
+		.driver_data = SAITEK_RELEASE_MODE_RAT7 },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_SAITEK, USB_DEVICE_ID_SAITEK_RAT7_OLD),
+		.driver_data = SAITEK_RELEASE_MODE_RAT7 },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_SAITEK, USB_DEVICE_ID_SAITEK_RAT7),
+		.driver_data = SAITEK_RELEASE_MODE_RAT7 },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_SAITEK, USB_DEVICE_ID_SAITEK_RAT7_CONTAGION),
+		.driver_data = SAITEK_RELEASE_MODE_RAT7 },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_SAITEK, USB_DEVICE_ID_SAITEK_RAT9),
+		.driver_data = SAITEK_RELEASE_MODE_RAT7 },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_MADCATZ, USB_DEVICE_ID_MADCATZ_RAT9),
+		.driver_data = SAITEK_RELEASE_MODE_RAT7 },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_SAITEK, USB_DEVICE_ID_SAITEK_MMO7),
+		.driver_data = SAITEK_RELEASE_MODE_MMO7 },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_MADCATZ, USB_DEVICE_ID_MADCATZ_MMO7),
+		.driver_data = SAITEK_RELEASE_MODE_MMO7 },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(hid, saitek_devices);
+
+static struct hid_driver saitek_driver = {
+	.name = "saitek",
+	.id_table = saitek_devices,
+	.probe = saitek_probe,
+	.report_fixup = saitek_report_fixup,
+	.raw_event = saitek_raw_event,
+	.event = saitek_event,
+};
+module_hid_driver(saitek_driver);
+
+MODULE_DESCRIPTION("HID driver for Saitek devices.");
+MODULE_LICENSE("GPL");