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, 485 insertions, 0 deletions

diff --git a/drivers/usb/serial/ir-usb.c b/drivers/usb/serial/ir-usb.c
new file mode 100644
index 000000000..aac845397
--- /dev/null
+++ b/drivers/usb/serial/ir-usb.c
@@ -0,0 +1,485 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * USB IR Dongle driver
+ *
+ *	Copyright (C) 2001-2002	Greg Kroah-Hartman (greg@kroah.com)
+ *	Copyright (C) 2002	Gary Brubaker (xavyer@ix.netcom.com)
+ *	Copyright (C) 2010	Johan Hovold (jhovold@gmail.com)
+ *
+ * This driver allows a USB IrDA device to be used as a "dumb" serial device.
+ * This can be useful if you do not have access to a full IrDA stack on the
+ * other side of the connection.  If you do have an IrDA stack on both devices,
+ * please use the usb-irda driver, as it contains the proper error checking and
+ * other goodness of a full IrDA stack.
+ *
+ * Portions of this driver were taken from drivers/net/irda/irda-usb.c, which
+ * was written by Roman Weissgaerber <weissg@vienna.at>, Dag Brattli
+ * <dag@brattli.net>, and Jean Tourrilhes <jt@hpl.hp.com>
+ *
+ * See Documentation/usb/usb-serial.rst for more information on using this
+ * driver
+ */
+
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/init.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>
+#include <linux/usb/irda.h>
+
+#define DRIVER_AUTHOR "Greg Kroah-Hartman <greg@kroah.com>, Johan Hovold <jhovold@gmail.com>"
+#define DRIVER_DESC "USB IR Dongle driver"
+
+/* if overridden by the user, then use their value for the size of the read and
+ * write urbs */
+static int buffer_size;
+
+/* if overridden by the user, then use the specified number of XBOFs */
+static int xbof = -1;
+
+static int  ir_startup (struct usb_serial *serial);
+static int ir_write(struct tty_struct *tty, struct usb_serial_port *port,
+		const unsigned char *buf, int count);
+static unsigned int ir_write_room(struct tty_struct *tty);
+static void ir_write_bulk_callback(struct urb *urb);
+static void ir_process_read_urb(struct urb *urb);
+static void ir_set_termios(struct tty_struct *tty,
+			   struct usb_serial_port *port,
+			   const struct ktermios *old_termios);
+
+/* Not that this lot means you can only have one per system */
+static u8 ir_baud;
+static u8 ir_xbof;
+static u8 ir_add_bof;
+
+static const struct usb_device_id ir_id_table[] = {
+	{ USB_DEVICE(0x050f, 0x0180) },		/* KC Technology, KC-180 */
+	{ USB_DEVICE(0x08e9, 0x0100) },		/* XTNDAccess */
+	{ USB_DEVICE(0x09c4, 0x0011) },		/* ACTiSys ACT-IR2000U */
+	{ USB_INTERFACE_INFO(USB_CLASS_APP_SPEC, USB_SUBCLASS_IRDA, 0) },
+	{ }					/* Terminating entry */
+};
+
+MODULE_DEVICE_TABLE(usb, ir_id_table);
+
+static struct usb_serial_driver ir_device = {
+	.driver	= {
+		.name	= "ir-usb",
+	},
+	.description		= "IR Dongle",
+	.id_table		= ir_id_table,
+	.num_ports		= 1,
+	.num_bulk_in		= 1,
+	.num_bulk_out		= 1,
+	.set_termios		= ir_set_termios,
+	.attach			= ir_startup,
+	.write			= ir_write,
+	.write_room		= ir_write_room,
+	.write_bulk_callback	= ir_write_bulk_callback,
+	.process_read_urb	= ir_process_read_urb,
+};
+
+static struct usb_serial_driver * const serial_drivers[] = {
+	&ir_device, NULL
+};
+
+static inline void irda_usb_dump_class_desc(struct usb_serial *serial,
+					    struct usb_irda_cs_descriptor *desc)
+{
+	struct device *dev = &serial->dev->dev;
+
+	dev_dbg(dev, "bLength=%x\n", desc->bLength);
+	dev_dbg(dev, "bDescriptorType=%x\n", desc->bDescriptorType);
+	dev_dbg(dev, "bcdSpecRevision=%x\n", __le16_to_cpu(desc->bcdSpecRevision));
+	dev_dbg(dev, "bmDataSize=%x\n", desc->bmDataSize);
+	dev_dbg(dev, "bmWindowSize=%x\n", desc->bmWindowSize);
+	dev_dbg(dev, "bmMinTurnaroundTime=%d\n", desc->bmMinTurnaroundTime);
+	dev_dbg(dev, "wBaudRate=%x\n", __le16_to_cpu(desc->wBaudRate));
+	dev_dbg(dev, "bmAdditionalBOFs=%x\n", desc->bmAdditionalBOFs);
+	dev_dbg(dev, "bIrdaRateSniff=%x\n", desc->bIrdaRateSniff);
+	dev_dbg(dev, "bMaxUnicastList=%x\n", desc->bMaxUnicastList);
+}
+
+/*------------------------------------------------------------------*/
+/*
+ * Function irda_usb_find_class_desc(dev, ifnum)
+ *
+ *    Returns instance of IrDA class descriptor, or NULL if not found
+ *
+ * The class descriptor is some extra info that IrDA USB devices will
+ * offer to us, describing their IrDA characteristics. We will use that in
+ * irda_usb_init_qos()
+ *
+ * Based on the same function in drivers/net/irda/irda-usb.c
+ */
+static struct usb_irda_cs_descriptor *
+irda_usb_find_class_desc(struct usb_serial *serial, unsigned int ifnum)
+{
+	struct usb_device *dev = serial->dev;
+	struct usb_irda_cs_descriptor *desc;
+	int ret;
+
+	desc = kzalloc_obj(*desc);
+	if (!desc)
+		return NULL;
+
+	ret = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0),
+			USB_REQ_CS_IRDA_GET_CLASS_DESC,
+			USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
+			0, ifnum, desc, sizeof(*desc), 1000);
+
+	dev_dbg(&serial->dev->dev, "%s -  ret=%d\n", __func__, ret);
+	if (ret < (int)sizeof(*desc)) {
+		dev_dbg(&serial->dev->dev,
+			"%s - class descriptor read %s (%d)\n", __func__,
+			(ret < 0) ? "failed" : "too short", ret);
+		goto error;
+	}
+	if (desc->bDescriptorType != USB_DT_CS_IRDA) {
+		dev_dbg(&serial->dev->dev, "%s - bad class descriptor type\n",
+			__func__);
+		goto error;
+	}
+
+	irda_usb_dump_class_desc(serial, desc);
+	return desc;
+
+error:
+	kfree(desc);
+	return NULL;
+}
+
+static u8 ir_xbof_change(u8 xbof)
+{
+	u8 result;
+
+	/* reference irda-usb.c */
+	switch (xbof) {
+	case 48:
+		result = 0x10;
+		break;
+	case 28:
+	case 24:
+		result = 0x20;
+		break;
+	default:
+	case 12:
+		result = 0x30;
+		break;
+	case  5:
+	case  6:
+		result = 0x40;
+		break;
+	case  3:
+		result = 0x50;
+		break;
+	case  2:
+		result = 0x60;
+		break;
+	case  1:
+		result = 0x70;
+		break;
+	case  0:
+		result = 0x80;
+		break;
+	}
+
+	return(result);
+}
+
+static int ir_startup(struct usb_serial *serial)
+{
+	struct usb_irda_cs_descriptor *irda_desc;
+	int rates;
+
+	irda_desc = irda_usb_find_class_desc(serial, 0);
+	if (!irda_desc) {
+		dev_err(&serial->dev->dev,
+			"IRDA class descriptor not found, device not bound\n");
+		return -ENODEV;
+	}
+
+	rates = le16_to_cpu(irda_desc->wBaudRate);
+
+	dev_dbg(&serial->dev->dev,
+		"%s - Baud rates supported:%s%s%s%s%s%s%s%s%s\n",
+		__func__,
+		(rates & USB_IRDA_BR_2400) ? " 2400" : "",
+		(rates & USB_IRDA_BR_9600) ? " 9600" : "",
+		(rates & USB_IRDA_BR_19200) ? " 19200" : "",
+		(rates & USB_IRDA_BR_38400) ? " 38400" : "",
+		(rates & USB_IRDA_BR_57600) ? " 57600" : "",
+		(rates & USB_IRDA_BR_115200) ? " 115200" : "",
+		(rates & USB_IRDA_BR_576000) ? " 576000" : "",
+		(rates & USB_IRDA_BR_1152000) ? " 1152000" : "",
+		(rates & USB_IRDA_BR_4000000) ? " 4000000" : "");
+
+	switch (irda_desc->bmAdditionalBOFs) {
+	case USB_IRDA_AB_48:
+		ir_add_bof = 48;
+		break;
+	case USB_IRDA_AB_24:
+		ir_add_bof = 24;
+		break;
+	case USB_IRDA_AB_12:
+		ir_add_bof = 12;
+		break;
+	case USB_IRDA_AB_6:
+		ir_add_bof = 6;
+		break;
+	case USB_IRDA_AB_3:
+		ir_add_bof = 3;
+		break;
+	case USB_IRDA_AB_2:
+		ir_add_bof = 2;
+		break;
+	case USB_IRDA_AB_1:
+		ir_add_bof = 1;
+		break;
+	case USB_IRDA_AB_0:
+		ir_add_bof = 0;
+		break;
+	default:
+		break;
+	}
+
+	kfree(irda_desc);
+
+	return 0;
+}
+
+static int ir_write(struct tty_struct *tty, struct usb_serial_port *port,
+		const unsigned char *buf, int count)
+{
+	struct urb *urb = NULL;
+	unsigned long flags;
+	int ret;
+
+	if (port->bulk_out_size == 0)
+		return -EINVAL;
+
+	if (count == 0)
+		return 0;
+
+	count = min(count, port->bulk_out_size - 1);
+
+	spin_lock_irqsave(&port->lock, flags);
+	if (__test_and_clear_bit(0, &port->write_urbs_free)) {
+		urb = port->write_urbs[0];
+		port->tx_bytes += count;
+	}
+	spin_unlock_irqrestore(&port->lock, flags);
+
+	if (!urb)
+		return 0;
+
+	/*
+	 * The first byte of the packet we send to the device contains an
+	 * outbound header which indicates an additional number of BOFs and
+	 * a baud rate change.
+	 *
+	 * See section 5.4.2.2 of the USB IrDA spec.
+	 */
+	*(u8 *)urb->transfer_buffer = ir_xbof | ir_baud;
+
+	memcpy(urb->transfer_buffer + 1, buf, count);
+
+	urb->transfer_buffer_length = count + 1;
+	urb->transfer_flags = URB_ZERO_PACKET;
+
+	ret = usb_submit_urb(urb, GFP_ATOMIC);
+	if (ret) {
+		dev_err(&port->dev, "failed to submit write urb: %d\n", ret);
+
+		spin_lock_irqsave(&port->lock, flags);
+		__set_bit(0, &port->write_urbs_free);
+		port->tx_bytes -= count;
+		spin_unlock_irqrestore(&port->lock, flags);
+
+		return ret;
+	}
+
+	return count;
+}
+
+static void ir_write_bulk_callback(struct urb *urb)
+{
+	struct usb_serial_port *port = urb->context;
+	int status = urb->status;
+	unsigned long flags;
+
+	spin_lock_irqsave(&port->lock, flags);
+	__set_bit(0, &port->write_urbs_free);
+	port->tx_bytes -= urb->transfer_buffer_length - 1;
+	spin_unlock_irqrestore(&port->lock, flags);
+
+	switch (status) {
+	case 0:
+		break;
+	case -ENOENT:
+	case -ECONNRESET:
+	case -ESHUTDOWN:
+		dev_dbg(&port->dev, "write urb stopped: %d\n", status);
+		return;
+	case -EPIPE:
+		dev_err(&port->dev, "write urb stopped: %d\n", status);
+		return;
+	default:
+		dev_err(&port->dev, "nonzero write-urb status: %d\n", status);
+		break;
+	}
+
+	usb_serial_port_softint(port);
+}
+
+static unsigned int ir_write_room(struct tty_struct *tty)
+{
+	struct usb_serial_port *port = tty->driver_data;
+	unsigned int count = 0;
+
+	if (port->bulk_out_size == 0)
+		return 0;
+
+	if (test_bit(0, &port->write_urbs_free))
+		count = port->bulk_out_size - 1;
+
+	return count;
+}
+
+static void ir_process_read_urb(struct urb *urb)
+{
+	struct usb_serial_port *port = urb->context;
+	unsigned char *data = urb->transfer_buffer;
+
+	if (!urb->actual_length)
+		return;
+	/*
+	 * The first byte of the packet we get from the device
+	 * contains a busy indicator and baud rate change.
+	 * See section 5.4.1.2 of the USB IrDA spec.
+	 */
+	if (*data & 0x0f)
+		ir_baud = *data & 0x0f;
+
+	if (urb->actual_length == 1)
+		return;
+
+	tty_insert_flip_string(&port->port, data + 1, urb->actual_length - 1);
+	tty_flip_buffer_push(&port->port);
+}
+
+static void ir_set_termios(struct tty_struct *tty,
+			   struct usb_serial_port *port,
+			   const struct ktermios *old_termios)
+{
+	struct usb_device *udev = port->serial->dev;
+	unsigned char *transfer_buffer;
+	int actual_length;
+	speed_t baud;
+	int ir_baud;
+	int ret;
+
+	baud = tty_get_baud_rate(tty);
+
+	/*
+	 * FIXME, we should compare the baud request against the
+	 * capability stated in the IR header that we got in the
+	 * startup function.
+	 */
+
+	switch (baud) {
+	case 2400:
+		ir_baud = USB_IRDA_LS_2400;
+		break;
+	case 9600:
+		ir_baud = USB_IRDA_LS_9600;
+		break;
+	case 19200:
+		ir_baud = USB_IRDA_LS_19200;
+		break;
+	case 38400:
+		ir_baud = USB_IRDA_LS_38400;
+		break;
+	case 57600:
+		ir_baud = USB_IRDA_LS_57600;
+		break;
+	case 115200:
+		ir_baud = USB_IRDA_LS_115200;
+		break;
+	case 576000:
+		ir_baud = USB_IRDA_LS_576000;
+		break;
+	case 1152000:
+		ir_baud = USB_IRDA_LS_1152000;
+		break;
+	case 4000000:
+		ir_baud = USB_IRDA_LS_4000000;
+		break;
+	default:
+		ir_baud = USB_IRDA_LS_9600;
+		baud = 9600;
+	}
+
+	if (xbof == -1)
+		ir_xbof = ir_xbof_change(ir_add_bof);
+	else
+		ir_xbof = ir_xbof_change(xbof) ;
+
+	/* Only speed changes are supported */
+	tty_termios_copy_hw(&tty->termios, old_termios);
+	tty_encode_baud_rate(tty, baud, baud);
+
+	/*
+	 * send the baud change out on an "empty" data packet
+	 */
+	transfer_buffer = kmalloc(1, GFP_KERNEL);
+	if (!transfer_buffer)
+		return;
+
+	*transfer_buffer = ir_xbof | ir_baud;
+
+	ret = usb_bulk_msg(udev,
+			usb_sndbulkpipe(udev, port->bulk_out_endpointAddress),
+			transfer_buffer, 1, &actual_length, 5000);
+	if (ret || actual_length != 1) {
+		if (!ret)
+			ret = -EIO;
+		dev_err(&port->dev, "failed to change line speed: %d\n", ret);
+	}
+
+	kfree(transfer_buffer);
+}
+
+static int __init ir_init(void)
+{
+	if (buffer_size) {
+		ir_device.bulk_in_size = buffer_size;
+		ir_device.bulk_out_size = buffer_size;
+	}
+
+	return usb_serial_register_drivers(serial_drivers, KBUILD_MODNAME, ir_id_table);
+}
+
+static void __exit ir_exit(void)
+{
+	usb_serial_deregister_drivers(serial_drivers);
+}
+
+
+module_init(ir_init);
+module_exit(ir_exit);
+
+MODULE_AUTHOR(DRIVER_AUTHOR);
+MODULE_DESCRIPTION(DRIVER_DESC);
+MODULE_LICENSE("GPL");
+
+module_param(xbof, int, 0);
+MODULE_PARM_DESC(xbof, "Force specific number of XBOFs");
+module_param(buffer_size, int, 0);
+MODULE_PARM_DESC(buffer_size, "Size of the transfer buffers");
+