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, 292 insertions, 0 deletions

diff --git a/drivers/input/touchscreen/tps6507x-ts.c b/drivers/input/touchscreen/tps6507x-ts.c
new file mode 100644
index 000000000..f48871767
--- /dev/null
+++ b/drivers/input/touchscreen/tps6507x-ts.c
@@ -0,0 +1,292 @@
+/*
+ * Touchscreen driver for the tps6507x chip.
+ *
+ * Copyright (c) 2009 RidgeRun (todd.fischer@ridgerun.com)
+ *
+ * Credits:
+ *
+ *    Using code from tsc2007, MtekVision Co., Ltd.
+ *
+ * For licencing details see kernel-base/COPYING
+ *
+ * TPS65070, TPS65073, TPS650731, and TPS650732 support
+ * 10 bit touch screen interface.
+ */
+
+#include <linux/module.h>
+#include <linux/workqueue.h>
+#include <linux/slab.h>
+#include <linux/input.h>
+#include <linux/platform_device.h>
+#include <linux/mfd/tps6507x.h>
+#include <linux/input/tps6507x-ts.h>
+#include <linux/delay.h>
+
+#define TSC_DEFAULT_POLL_PERIOD 30 /* ms */
+#define TPS_DEFAULT_MIN_PRESSURE 0x30
+#define MAX_10BIT ((1 << 10) - 1)
+
+#define	TPS6507X_ADCONFIG_CONVERT_TS (TPS6507X_ADCONFIG_AD_ENABLE | \
+					 TPS6507X_ADCONFIG_START_CONVERSION | \
+					 TPS6507X_ADCONFIG_INPUT_REAL_TSC)
+#define	TPS6507X_ADCONFIG_POWER_DOWN_TS (TPS6507X_ADCONFIG_INPUT_REAL_TSC)
+
+struct ts_event {
+	u16	x;
+	u16	y;
+	u16	pressure;
+};
+
+struct tps6507x_ts {
+	struct device		*dev;
+	struct input_dev	*input;
+	struct tps6507x_dev	*mfd;
+	char			phys[32];
+	struct ts_event		tc;
+	u16			min_pressure;
+	bool			pendown;
+};
+
+static int tps6507x_read_u8(struct tps6507x_ts *tsc, u8 reg, u8 *data)
+{
+	return tsc->mfd->read_dev(tsc->mfd, reg, 1, data);
+}
+
+static int tps6507x_write_u8(struct tps6507x_ts *tsc, u8 reg, u8 data)
+{
+	return tsc->mfd->write_dev(tsc->mfd, reg, 1, &data);
+}
+
+static s32 tps6507x_adc_conversion(struct tps6507x_ts *tsc,
+				   u8 tsc_mode, u16 *value)
+{
+	s32 ret;
+	u8 adc_status;
+	u8 result;
+
+	/* Route input signal to A/D converter */
+
+	ret = tps6507x_write_u8(tsc, TPS6507X_REG_TSCMODE, tsc_mode);
+	if (ret) {
+		dev_err(tsc->dev, "TSC mode read failed\n");
+		goto err;
+	}
+
+	/* Start A/D conversion */
+
+	ret = tps6507x_write_u8(tsc, TPS6507X_REG_ADCONFIG,
+				TPS6507X_ADCONFIG_CONVERT_TS);
+	if (ret) {
+		dev_err(tsc->dev, "ADC config write failed\n");
+		return ret;
+	}
+
+	do {
+		ret = tps6507x_read_u8(tsc, TPS6507X_REG_ADCONFIG,
+				       &adc_status);
+		if (ret) {
+			dev_err(tsc->dev, "ADC config read failed\n");
+			goto err;
+		}
+	} while (adc_status & TPS6507X_ADCONFIG_START_CONVERSION);
+
+	ret = tps6507x_read_u8(tsc, TPS6507X_REG_ADRESULT_2, &result);
+	if (ret) {
+		dev_err(tsc->dev, "ADC result 2 read failed\n");
+		goto err;
+	}
+
+	*value = (result & TPS6507X_REG_ADRESULT_2_MASK) << 8;
+
+	ret = tps6507x_read_u8(tsc, TPS6507X_REG_ADRESULT_1, &result);
+	if (ret) {
+		dev_err(tsc->dev, "ADC result 1 read failed\n");
+		goto err;
+	}
+
+	*value |= result;
+
+	dev_dbg(tsc->dev, "TSC channel %d = 0x%X\n", tsc_mode, *value);
+
+err:
+	return ret;
+}
+
+/* Need to call tps6507x_adc_standby() after using A/D converter for the
+ * touch screen interrupt to work properly.
+ */
+
+static s32 tps6507x_adc_standby(struct tps6507x_ts *tsc)
+{
+	s32 ret;
+	u8 val;
+
+	ret = tps6507x_write_u8(tsc,  TPS6507X_REG_ADCONFIG,
+				TPS6507X_ADCONFIG_INPUT_TSC);
+	if (ret)
+		return ret;
+
+	ret = tps6507x_write_u8(tsc, TPS6507X_REG_TSCMODE,
+				TPS6507X_TSCMODE_STANDBY);
+	if (ret)
+		return ret;
+
+	ret = tps6507x_read_u8(tsc, TPS6507X_REG_INT, &val);
+	if (ret)
+		return ret;
+
+	while (val & TPS6507X_REG_TSC_INT) {
+		mdelay(10);
+		ret = tps6507x_read_u8(tsc, TPS6507X_REG_INT, &val);
+		if (ret)
+			return ret;
+	}
+
+	return ret;
+}
+
+static void tps6507x_ts_poll(struct input_dev *input_dev)
+{
+	struct tps6507x_ts *tsc = input_get_drvdata(input_dev);
+	bool pendown;
+	s32 ret;
+
+	ret = tps6507x_adc_conversion(tsc, TPS6507X_TSCMODE_PRESSURE,
+				      &tsc->tc.pressure);
+	if (ret)
+		goto done;
+
+	pendown = tsc->tc.pressure > tsc->min_pressure;
+
+	if (unlikely(!pendown && tsc->pendown)) {
+		dev_dbg(tsc->dev, "UP\n");
+		input_report_key(input_dev, BTN_TOUCH, 0);
+		input_report_abs(input_dev, ABS_PRESSURE, 0);
+		input_sync(input_dev);
+		tsc->pendown = false;
+	}
+
+	if (pendown) {
+
+		if (!tsc->pendown) {
+			dev_dbg(tsc->dev, "DOWN\n");
+			input_report_key(input_dev, BTN_TOUCH, 1);
+		} else
+			dev_dbg(tsc->dev, "still down\n");
+
+		ret =  tps6507x_adc_conversion(tsc, TPS6507X_TSCMODE_X_POSITION,
+					       &tsc->tc.x);
+		if (ret)
+			goto done;
+
+		ret =  tps6507x_adc_conversion(tsc, TPS6507X_TSCMODE_Y_POSITION,
+					       &tsc->tc.y);
+		if (ret)
+			goto done;
+
+		input_report_abs(input_dev, ABS_X, tsc->tc.x);
+		input_report_abs(input_dev, ABS_Y, tsc->tc.y);
+		input_report_abs(input_dev, ABS_PRESSURE, tsc->tc.pressure);
+		input_sync(input_dev);
+		tsc->pendown = true;
+	}
+
+done:
+	tps6507x_adc_standby(tsc);
+}
+
+static int tps6507x_ts_probe(struct platform_device *pdev)
+{
+	struct tps6507x_dev *tps6507x_dev = dev_get_drvdata(pdev->dev.parent);
+	const struct tps6507x_board *tps_board;
+	const struct touchscreen_init_data *init_data;
+	struct tps6507x_ts *tsc;
+	struct input_dev *input_dev;
+	int error;
+
+	/*
+	 * tps_board points to pmic related constants
+	 * coming from the board-evm file.
+	 */
+	tps_board = dev_get_platdata(tps6507x_dev->dev);
+	if (!tps_board) {
+		dev_err(tps6507x_dev->dev,
+			"Could not find tps6507x platform data\n");
+		return -ENODEV;
+	}
+
+	/*
+	 * init_data points to array of regulator_init structures
+	 * coming from the board-evm file.
+	 */
+	init_data = tps_board->tps6507x_ts_init_data;
+
+	tsc = devm_kzalloc(&pdev->dev, sizeof(struct tps6507x_ts), GFP_KERNEL);
+	if (!tsc) {
+		dev_err(tps6507x_dev->dev, "failed to allocate driver data\n");
+		return -ENOMEM;
+	}
+
+	tsc->mfd = tps6507x_dev;
+	tsc->dev = tps6507x_dev->dev;
+	tsc->min_pressure = init_data ?
+			init_data->min_pressure : TPS_DEFAULT_MIN_PRESSURE;
+
+	snprintf(tsc->phys, sizeof(tsc->phys),
+		 "%s/input0", dev_name(tsc->dev));
+
+	input_dev = devm_input_allocate_device(&pdev->dev);
+	if (!input_dev) {
+		dev_err(tsc->dev, "Failed to allocate polled input device.\n");
+		return -ENOMEM;
+	}
+
+	tsc->input = input_dev;
+	input_set_drvdata(input_dev, tsc);
+
+	input_set_capability(input_dev, EV_KEY, BTN_TOUCH);
+	input_set_abs_params(input_dev, ABS_X, 0, MAX_10BIT, 0, 0);
+	input_set_abs_params(input_dev, ABS_Y, 0, MAX_10BIT, 0, 0);
+	input_set_abs_params(input_dev, ABS_PRESSURE, 0, MAX_10BIT, 0, 0);
+
+	input_dev->name = "TPS6507x Touchscreen";
+	input_dev->phys = tsc->phys;
+	input_dev->dev.parent = tsc->dev;
+	input_dev->id.bustype = BUS_I2C;
+	if (init_data) {
+		input_dev->id.vendor = init_data->vendor;
+		input_dev->id.product = init_data->product;
+		input_dev->id.version = init_data->version;
+	}
+
+	error = tps6507x_adc_standby(tsc);
+	if (error)
+		return error;
+
+	error = input_setup_polling(input_dev, tps6507x_ts_poll);
+	if (error)
+		return error;
+
+	input_set_poll_interval(input_dev,
+				init_data ? init_data->poll_period :
+					    TSC_DEFAULT_POLL_PERIOD);
+
+	error = input_register_device(input_dev);
+	if (error)
+		return error;
+
+	return 0;
+}
+
+static struct platform_driver tps6507x_ts_driver = {
+	.driver = {
+		.name = "tps6507x-ts",
+	},
+	.probe = tps6507x_ts_probe,
+};
+module_platform_driver(tps6507x_ts_driver);
+
+MODULE_AUTHOR("Todd Fischer <todd.fischer@ridgerun.com>");
+MODULE_DESCRIPTION("TPS6507x - TouchScreen driver");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:tps6507x-ts");