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, 420 insertions, 0 deletions

diff --git a/drivers/usb/serial/cyberjack.c b/drivers/usb/serial/cyberjack.c
new file mode 100644
index 000000000..57e20eb02
--- /dev/null
+++ b/drivers/usb/serial/cyberjack.c
@@ -0,0 +1,420 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ *  REINER SCT cyberJack pinpad/e-com USB Chipcard Reader Driver
+ *
+ *  Copyright (C) 2001  REINER SCT
+ *  Author: Matthias Bruestle
+ *
+ *  Contact: support@reiner-sct.com (see MAINTAINERS)
+ *
+ *  This program is largely derived from work by the linux-usb group
+ *  and associated source files.  Please see the usb/serial files for
+ *  individual credits and copyrights.
+ *
+ *  Thanks to Greg Kroah-Hartman (greg@kroah.com) for his help and
+ *  patience.
+ *
+ *  In case of problems, please write to the contact e-mail address
+ *  mentioned above.
+ *
+ *  Please note that later models of the cyberjack reader family are
+ *  supported by a libusb-based userspace device driver.
+ *
+ *  Homepage: http://www.reiner-sct.de/support/treiber_cyberjack.php#linux
+ */
+
+
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/slab.h>
+#include <linux/tty.h>
+#include <linux/tty_flip.h>
+#include <linux/module.h>
+#include <linux/spinlock.h>
+#include <linux/usb.h>
+#include <linux/usb/serial.h>
+
+#define CYBERJACK_LOCAL_BUF_SIZE 32
+
+#define DRIVER_AUTHOR "Matthias Bruestle"
+#define DRIVER_DESC "REINER SCT cyberJack pinpad/e-com USB Chipcard Reader Driver"
+
+
+#define CYBERJACK_VENDOR_ID	0x0C4B
+#define CYBERJACK_PRODUCT_ID	0x0100
+
+/* Function prototypes */
+static int cyberjack_port_probe(struct usb_serial_port *port);
+static void cyberjack_port_remove(struct usb_serial_port *port);
+static int  cyberjack_open(struct tty_struct *tty,
+	struct usb_serial_port *port);
+static void cyberjack_close(struct usb_serial_port *port);
+static int cyberjack_write(struct tty_struct *tty,
+	struct usb_serial_port *port, const unsigned char *buf, int count);
+static unsigned int cyberjack_write_room(struct tty_struct *tty);
+static void cyberjack_read_int_callback(struct urb *urb);
+static void cyberjack_read_bulk_callback(struct urb *urb);
+static void cyberjack_write_bulk_callback(struct urb *urb);
+
+static const struct usb_device_id id_table[] = {
+	{ USB_DEVICE(CYBERJACK_VENDOR_ID, CYBERJACK_PRODUCT_ID) },
+	{ }			/* Terminating entry */
+};
+
+MODULE_DEVICE_TABLE(usb, id_table);
+
+static struct usb_serial_driver cyberjack_device = {
+	.driver = {
+		.name =		"cyberjack",
+	},
+	.description =		"Reiner SCT Cyberjack USB card reader",
+	.id_table =		id_table,
+	.num_ports =		1,
+	.num_bulk_out =		1,
+	.port_probe =		cyberjack_port_probe,
+	.port_remove =		cyberjack_port_remove,
+	.open =			cyberjack_open,
+	.close =		cyberjack_close,
+	.write =		cyberjack_write,
+	.write_room =		cyberjack_write_room,
+	.read_int_callback =	cyberjack_read_int_callback,
+	.read_bulk_callback =	cyberjack_read_bulk_callback,
+	.write_bulk_callback =	cyberjack_write_bulk_callback,
+};
+
+static struct usb_serial_driver * const serial_drivers[] = {
+	&cyberjack_device, NULL
+};
+
+struct cyberjack_private {
+	spinlock_t	lock;		/* Lock for SMP */
+	short		rdtodo;		/* Bytes still to read */
+	unsigned char	wrbuf[5*64];	/* Buffer for collecting data to write */
+	short		wrfilled;	/* Overall data size we already got */
+	short		wrsent;		/* Data already sent */
+};
+
+static int cyberjack_port_probe(struct usb_serial_port *port)
+{
+	struct cyberjack_private *priv;
+	int result;
+
+	priv = kmalloc_obj(struct cyberjack_private);
+	if (!priv)
+		return -ENOMEM;
+
+	spin_lock_init(&priv->lock);
+	priv->rdtodo = 0;
+	priv->wrfilled = 0;
+	priv->wrsent = 0;
+
+	usb_set_serial_port_data(port, priv);
+
+	result = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
+	if (result)
+		dev_err(&port->dev, "usb_submit_urb(read int) failed\n");
+
+	return 0;
+}
+
+static void cyberjack_port_remove(struct usb_serial_port *port)
+{
+	struct cyberjack_private *priv;
+
+	usb_kill_urb(port->interrupt_in_urb);
+
+	priv = usb_get_serial_port_data(port);
+	kfree(priv);
+}
+
+static int  cyberjack_open(struct tty_struct *tty,
+					struct usb_serial_port *port)
+{
+	struct cyberjack_private *priv;
+	unsigned long flags;
+
+	dev_dbg(&port->dev, "%s - usb_clear_halt\n", __func__);
+	usb_clear_halt(port->serial->dev, port->write_urb->pipe);
+
+	priv = usb_get_serial_port_data(port);
+	spin_lock_irqsave(&priv->lock, flags);
+	priv->rdtodo = 0;
+	priv->wrfilled = 0;
+	priv->wrsent = 0;
+	spin_unlock_irqrestore(&priv->lock, flags);
+
+	return 0;
+}
+
+static void cyberjack_close(struct usb_serial_port *port)
+{
+	usb_kill_urb(port->write_urb);
+	usb_kill_urb(port->read_urb);
+}
+
+static int cyberjack_write(struct tty_struct *tty,
+	struct usb_serial_port *port, const unsigned char *buf, int count)
+{
+	struct device *dev = &port->dev;
+	struct cyberjack_private *priv = usb_get_serial_port_data(port);
+	unsigned long flags;
+	int result;
+	int wrexpected;
+
+	if (count == 0) {
+		dev_dbg(dev, "%s - write request of 0 bytes\n", __func__);
+		return 0;
+	}
+
+	if (!test_and_clear_bit(0, &port->write_urbs_free)) {
+		dev_dbg(dev, "%s - already writing\n", __func__);
+		return 0;
+	}
+
+	spin_lock_irqsave(&priv->lock, flags);
+
+	if (count+priv->wrfilled > sizeof(priv->wrbuf)) {
+		/* To much data for buffer. Reset buffer. */
+		priv->wrfilled = 0;
+		spin_unlock_irqrestore(&priv->lock, flags);
+		set_bit(0, &port->write_urbs_free);
+		return 0;
+	}
+
+	/* Copy data */
+	memcpy(priv->wrbuf + priv->wrfilled, buf, count);
+
+	usb_serial_debug_data(dev, __func__, count, priv->wrbuf + priv->wrfilled);
+	priv->wrfilled += count;
+
+	if (priv->wrfilled >= 3) {
+		wrexpected = ((int)priv->wrbuf[2]<<8)+priv->wrbuf[1]+3;
+		dev_dbg(dev, "%s - expected data: %d\n", __func__, wrexpected);
+	} else
+		wrexpected = sizeof(priv->wrbuf);
+
+	if (priv->wrfilled >= wrexpected) {
+		/* We have enough data to begin transmission */
+		int length;
+
+		dev_dbg(dev, "%s - transmitting data (frame 1)\n", __func__);
+		length = (wrexpected > port->bulk_out_size) ?
+					port->bulk_out_size : wrexpected;
+
+		memcpy(port->write_urb->transfer_buffer, priv->wrbuf, length);
+		priv->wrsent = length;
+
+		/* set up our urb */
+		port->write_urb->transfer_buffer_length = length;
+
+		/* send the data out the bulk port */
+		result = usb_submit_urb(port->write_urb, GFP_ATOMIC);
+		if (result) {
+			dev_err(&port->dev,
+				"%s - failed submitting write urb, error %d\n",
+				__func__, result);
+			/* Throw away data. No better idea what to do with it. */
+			priv->wrfilled = 0;
+			priv->wrsent = 0;
+			spin_unlock_irqrestore(&priv->lock, flags);
+			set_bit(0, &port->write_urbs_free);
+			return 0;
+		}
+
+		dev_dbg(dev, "%s - priv->wrsent=%d\n", __func__, priv->wrsent);
+		dev_dbg(dev, "%s - priv->wrfilled=%d\n", __func__, priv->wrfilled);
+
+		if (priv->wrsent >= priv->wrfilled) {
+			dev_dbg(dev, "%s - buffer cleaned\n", __func__);
+			memset(priv->wrbuf, 0, sizeof(priv->wrbuf));
+			priv->wrfilled = 0;
+			priv->wrsent = 0;
+		}
+	}
+
+	spin_unlock_irqrestore(&priv->lock, flags);
+
+	return count;
+}
+
+static unsigned int cyberjack_write_room(struct tty_struct *tty)
+{
+	/* FIXME: .... */
+	return CYBERJACK_LOCAL_BUF_SIZE;
+}
+
+static void cyberjack_read_int_callback(struct urb *urb)
+{
+	struct usb_serial_port *port = urb->context;
+	struct cyberjack_private *priv = usb_get_serial_port_data(port);
+	struct device *dev = &port->dev;
+	unsigned char *data = urb->transfer_buffer;
+	int status = urb->status;
+	unsigned long flags;
+	int result;
+
+	/* the urb might have been killed. */
+	if (status)
+		return;
+
+	usb_serial_debug_data(dev, __func__, urb->actual_length, data);
+
+	/* React only to interrupts signaling a bulk_in transfer */
+	if (urb->actual_length == 4 && data[0] == 0x01) {
+		short old_rdtodo;
+
+		/* This is a announcement of coming bulk_ins. */
+		unsigned short size = ((unsigned short)data[3]<<8)+data[2]+3;
+
+		spin_lock_irqsave(&priv->lock, flags);
+
+		old_rdtodo = priv->rdtodo;
+
+		if (old_rdtodo > SHRT_MAX - size) {
+			dev_dbg(dev, "Too many bulk_in urbs to do.\n");
+			spin_unlock_irqrestore(&priv->lock, flags);
+			goto resubmit;
+		}
+
+		/* "+=" is probably more fault tolerant than "=" */
+		priv->rdtodo += size;
+
+		dev_dbg(dev, "%s - rdtodo: %d\n", __func__, priv->rdtodo);
+
+		spin_unlock_irqrestore(&priv->lock, flags);
+
+		if (!old_rdtodo) {
+			result = usb_submit_urb(port->read_urb, GFP_ATOMIC);
+			if (result)
+				dev_err(dev, "%s - failed resubmitting read urb, error %d\n",
+					__func__, result);
+			dev_dbg(dev, "%s - usb_submit_urb(read urb)\n", __func__);
+		}
+	}
+
+resubmit:
+	result = usb_submit_urb(port->interrupt_in_urb, GFP_ATOMIC);
+	if (result)
+		dev_err(&port->dev, "usb_submit_urb(read int) failed\n");
+	dev_dbg(dev, "%s - usb_submit_urb(int urb)\n", __func__);
+}
+
+static void cyberjack_read_bulk_callback(struct urb *urb)
+{
+	struct usb_serial_port *port = urb->context;
+	struct cyberjack_private *priv = usb_get_serial_port_data(port);
+	struct device *dev = &port->dev;
+	unsigned char *data = urb->transfer_buffer;
+	unsigned long flags;
+	short todo;
+	int result;
+	int status = urb->status;
+
+	usb_serial_debug_data(dev, __func__, urb->actual_length, data);
+	if (status) {
+		dev_dbg(dev, "%s - nonzero read bulk status received: %d\n",
+			__func__, status);
+		return;
+	}
+
+	if (urb->actual_length) {
+		tty_insert_flip_string(&port->port, data, urb->actual_length);
+		tty_flip_buffer_push(&port->port);
+	}
+
+	spin_lock_irqsave(&priv->lock, flags);
+
+	/* Reduce urbs to do by one. */
+	priv->rdtodo -= urb->actual_length;
+	/* Just to be sure */
+	if (priv->rdtodo < 0)
+		priv->rdtodo = 0;
+	todo = priv->rdtodo;
+
+	spin_unlock_irqrestore(&priv->lock, flags);
+
+	dev_dbg(dev, "%s - rdtodo: %d\n", __func__, todo);
+
+	/* Continue to read if we have still urbs to do. */
+	if (todo /* || (urb->actual_length==port->bulk_in_endpointAddress)*/) {
+		result = usb_submit_urb(port->read_urb, GFP_ATOMIC);
+		if (result)
+			dev_err(dev, "%s - failed resubmitting read urb, error %d\n",
+				__func__, result);
+		dev_dbg(dev, "%s - usb_submit_urb(read urb)\n", __func__);
+	}
+}
+
+static void cyberjack_write_bulk_callback(struct urb *urb)
+{
+	struct usb_serial_port *port = urb->context;
+	struct cyberjack_private *priv = usb_get_serial_port_data(port);
+	struct device *dev = &port->dev;
+	int status = urb->status;
+	unsigned long flags;
+	bool resubmitted = false;
+
+	if (status) {
+		dev_dbg(dev, "%s - nonzero write bulk status received: %d\n",
+			__func__, status);
+		set_bit(0, &port->write_urbs_free);
+		return;
+	}
+
+	spin_lock_irqsave(&priv->lock, flags);
+
+	/* only do something if we have more data to send */
+	if (priv->wrfilled) {
+		int length, blksize, result;
+
+		dev_dbg(dev, "%s - transmitting data (frame n)\n", __func__);
+
+		length = ((priv->wrfilled - priv->wrsent) > port->bulk_out_size) ?
+			port->bulk_out_size : (priv->wrfilled - priv->wrsent);
+
+		memcpy(port->write_urb->transfer_buffer,
+					priv->wrbuf + priv->wrsent, length);
+		priv->wrsent += length;
+
+		/* set up our urb */
+		port->write_urb->transfer_buffer_length = length;
+
+		/* send the data out the bulk port */
+		result = usb_submit_urb(port->write_urb, GFP_ATOMIC);
+		if (result) {
+			dev_err(dev, "%s - failed submitting write urb, error %d\n",
+				__func__, result);
+			/* Throw away data. No better idea what to do with it. */
+			priv->wrfilled = 0;
+			priv->wrsent = 0;
+			goto exit;
+		}
+
+		resubmitted = true;
+
+		dev_dbg(dev, "%s - priv->wrsent=%d\n", __func__, priv->wrsent);
+		dev_dbg(dev, "%s - priv->wrfilled=%d\n", __func__, priv->wrfilled);
+
+		blksize = ((int)priv->wrbuf[2]<<8)+priv->wrbuf[1]+3;
+
+		if (priv->wrsent >= priv->wrfilled ||
+					priv->wrsent >= blksize) {
+			dev_dbg(dev, "%s - buffer cleaned\n", __func__);
+			memset(priv->wrbuf, 0, sizeof(priv->wrbuf));
+			priv->wrfilled = 0;
+			priv->wrsent = 0;
+		}
+	}
+
+exit:
+	spin_unlock_irqrestore(&priv->lock, flags);
+	if (!resubmitted)
+		set_bit(0, &port->write_urbs_free);
+	usb_serial_port_softint(port);
+}
+
+module_usb_serial_driver(serial_drivers, id_table);
+
+MODULE_AUTHOR(DRIVER_AUTHOR);
+MODULE_DESCRIPTION(DRIVER_DESC);
+MODULE_LICENSE("GPL");