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, 283 insertions, 0 deletions

diff --git a/drivers/hwmon/powerz.c b/drivers/hwmon/powerz.c
new file mode 100644
index 000000000..6e1359144
--- /dev/null
+++ b/drivers/hwmon/powerz.c
@@ -0,0 +1,283 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  Copyright (C) 2023 Thomas Weißschuh <linux@weissschuh.net>
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/completion.h>
+#include <linux/device.h>
+#include <linux/dma-mapping.h>
+#include <linux/hwmon.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/types.h>
+#include <linux/usb.h>
+
+#define DRIVER_NAME	"powerz"
+#define POWERZ_EP_CMD_OUT	0x01
+#define POWERZ_EP_DATA_IN	0x81
+
+struct powerz_sensor_data {
+	u8 _unknown_1[8];
+	__le32 V_bus;
+	__le32 I_bus;
+	__le32 V_bus_avg;
+	__le32 I_bus_avg;
+	u8 _unknown_2[8];
+	u8 temp[2];
+	__le16 V_cc1;
+	__le16 V_cc2;
+	__le16 V_dp;
+	__le16 V_dm;
+	__le16 V_dd;
+	u8 _unknown_3[4];
+} __packed;
+
+struct powerz_priv {
+	__dma_from_device_group_begin();
+	char transfer_buffer[64];
+	__dma_from_device_group_end();
+	struct mutex mutex;
+	struct completion completion;
+	struct urb *urb;
+	int status;
+};
+
+static const struct hwmon_channel_info *const powerz_info[] = {
+	HWMON_CHANNEL_INFO(in,
+			   HWMON_I_INPUT | HWMON_I_LABEL | HWMON_I_AVERAGE,
+			   HWMON_I_INPUT | HWMON_I_LABEL,
+			   HWMON_I_INPUT | HWMON_I_LABEL,
+			   HWMON_I_INPUT | HWMON_I_LABEL,
+			   HWMON_I_INPUT | HWMON_I_LABEL,
+			   HWMON_I_INPUT | HWMON_I_LABEL),
+	HWMON_CHANNEL_INFO(curr,
+			   HWMON_C_INPUT | HWMON_C_LABEL | HWMON_C_AVERAGE),
+	    HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT | HWMON_T_LABEL),
+	NULL
+};
+
+static int powerz_read_string(struct device *dev, enum hwmon_sensor_types type,
+			      u32 attr, int channel, const char **str)
+{
+	if (type == hwmon_curr && attr == hwmon_curr_label) {
+		*str = "IBUS";
+	} else if (type == hwmon_in && attr == hwmon_in_label) {
+		if (channel == 0)
+			*str = "VBUS";
+		else if (channel == 1)
+			*str = "VCC1";
+		else if (channel == 2)
+			*str = "VCC2";
+		else if (channel == 3)
+			*str = "VDP";
+		else if (channel == 4)
+			*str = "VDM";
+		else if (channel == 5)
+			*str = "VDD";
+		else
+			return -EOPNOTSUPP;
+	} else if (type == hwmon_temp && attr == hwmon_temp_label) {
+		*str = "TEMP";
+	} else {
+		return -EOPNOTSUPP;
+	}
+
+	return 0;
+}
+
+static void powerz_usb_data_complete(struct urb *urb)
+{
+	struct powerz_priv *priv = urb->context;
+
+	complete(&priv->completion);
+}
+
+static void powerz_usb_cmd_complete(struct urb *urb)
+{
+	struct powerz_priv *priv = urb->context;
+
+	usb_fill_bulk_urb(urb, urb->dev,
+			  usb_rcvbulkpipe(urb->dev, POWERZ_EP_DATA_IN),
+			  priv->transfer_buffer, sizeof(priv->transfer_buffer),
+			  powerz_usb_data_complete, priv);
+
+	priv->status = usb_submit_urb(urb, GFP_ATOMIC);
+	if (priv->status)
+		complete(&priv->completion);
+}
+
+static int powerz_read_data(struct usb_device *udev, struct powerz_priv *priv)
+{
+	long rc;
+	int ret;
+
+	if (!priv->urb)
+		return -ENODEV;
+
+	priv->status = -ETIMEDOUT;
+	reinit_completion(&priv->completion);
+
+	priv->transfer_buffer[0] = 0x0c;
+	priv->transfer_buffer[1] = 0x00;
+	priv->transfer_buffer[2] = 0x02;
+	priv->transfer_buffer[3] = 0x00;
+
+	usb_fill_bulk_urb(priv->urb, udev,
+			  usb_sndbulkpipe(udev, POWERZ_EP_CMD_OUT),
+			  priv->transfer_buffer, 4, powerz_usb_cmd_complete,
+			  priv);
+	ret = usb_submit_urb(priv->urb, GFP_KERNEL);
+	if (ret)
+		return ret;
+
+	rc = wait_for_completion_interruptible_timeout(&priv->completion,
+						       msecs_to_jiffies(5));
+	if (rc < 0) {
+		usb_kill_urb(priv->urb);
+		return rc;
+	}
+
+	if (rc == 0) {
+		usb_kill_urb(priv->urb);
+		return -EIO;
+	}
+
+	if (priv->urb->actual_length < sizeof(struct powerz_sensor_data))
+		return -EIO;
+
+	return priv->status;
+}
+
+static int powerz_read(struct device *dev, enum hwmon_sensor_types type,
+		       u32 attr, int channel, long *val)
+{
+	struct usb_interface *intf = to_usb_interface(dev->parent);
+	struct usb_device *udev = interface_to_usbdev(intf);
+	struct powerz_priv *priv = usb_get_intfdata(intf);
+	struct powerz_sensor_data *data;
+	int ret;
+
+	if (!priv)
+		return -EIO;	/* disconnected */
+
+	mutex_lock(&priv->mutex);
+	ret = powerz_read_data(udev, priv);
+	if (ret)
+		goto out;
+
+	data = (struct powerz_sensor_data *)priv->transfer_buffer;
+
+	if (type == hwmon_curr) {
+		if (attr == hwmon_curr_input)
+			*val = ((s32)le32_to_cpu(data->I_bus)) / 1000;
+		else if (attr == hwmon_curr_average)
+			*val = ((s32)le32_to_cpu(data->I_bus_avg)) / 1000;
+		else
+			ret = -EOPNOTSUPP;
+	} else if (type == hwmon_in) {
+		if (attr == hwmon_in_input) {
+			if (channel == 0)
+				*val = le32_to_cpu(data->V_bus) / 1000;
+			else if (channel == 1)
+				*val = le16_to_cpu(data->V_cc1) / 10;
+			else if (channel == 2)
+				*val = le16_to_cpu(data->V_cc2) / 10;
+			else if (channel == 3)
+				*val = le16_to_cpu(data->V_dp) / 10;
+			else if (channel == 4)
+				*val = le16_to_cpu(data->V_dm) / 10;
+			else if (channel == 5)
+				*val = le16_to_cpu(data->V_dd) / 10;
+			else
+				ret = -EOPNOTSUPP;
+		} else if (attr == hwmon_in_average && channel == 0) {
+			*val = le32_to_cpu(data->V_bus_avg) / 1000;
+		} else {
+			ret = -EOPNOTSUPP;
+		}
+	} else if (type == hwmon_temp && attr == hwmon_temp_input) {
+		*val = data->temp[1] * 2000 + data->temp[0] * 1000 / 128;
+	} else {
+		ret = -EOPNOTSUPP;
+	}
+
+out:
+	mutex_unlock(&priv->mutex);
+	return ret;
+}
+
+static const struct hwmon_ops powerz_hwmon_ops = {
+	.visible = 0444,
+	.read = powerz_read,
+	.read_string = powerz_read_string,
+};
+
+static const struct hwmon_chip_info powerz_chip_info = {
+	.ops = &powerz_hwmon_ops,
+	.info = powerz_info,
+};
+
+static int powerz_probe(struct usb_interface *intf,
+			const struct usb_device_id *id)
+{
+	struct powerz_priv *priv;
+	struct device *hwmon_dev;
+	struct device *parent;
+
+	parent = &intf->dev;
+
+	priv = devm_kzalloc(parent, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->urb = usb_alloc_urb(0, GFP_KERNEL);
+	if (!priv->urb)
+		return -ENOMEM;
+	mutex_init(&priv->mutex);
+	init_completion(&priv->completion);
+
+	usb_set_intfdata(intf, priv);
+
+	hwmon_dev =
+	    devm_hwmon_device_register_with_info(parent, DRIVER_NAME, priv,
+						 &powerz_chip_info, NULL);
+	if (IS_ERR(hwmon_dev)) {
+		usb_free_urb(priv->urb);
+		return PTR_ERR(hwmon_dev);
+	}
+
+	return 0;
+}
+
+static void powerz_disconnect(struct usb_interface *intf)
+{
+	struct powerz_priv *priv = usb_get_intfdata(intf);
+
+	mutex_lock(&priv->mutex);
+	usb_kill_urb(priv->urb);
+	usb_free_urb(priv->urb);
+	priv->urb = NULL;
+	mutex_unlock(&priv->mutex);
+}
+
+static const struct usb_device_id powerz_id_table[] = {
+	{ USB_DEVICE_INTERFACE_NUMBER(0x5FC9, 0x0061, 0x00) },	/* ChargerLAB POWER-Z KM002C */
+	{ USB_DEVICE_INTERFACE_NUMBER(0x5FC9, 0x0063, 0x00) },	/* ChargerLAB POWER-Z KM003C */
+	{ }
+};
+
+MODULE_DEVICE_TABLE(usb, powerz_id_table);
+
+static struct usb_driver powerz_driver = {
+	.name = DRIVER_NAME,
+	.id_table = powerz_id_table,
+	.probe = powerz_probe,
+	.disconnect = powerz_disconnect,
+};
+
+module_usb_driver(powerz_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Thomas Weißschuh <linux@weissschuh.net>");
+MODULE_DESCRIPTION("ChargerLAB POWER-Z USB-C tester");