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, 451 insertions, 0 deletions

diff --git a/drivers/bluetooth/bpa10x.c b/drivers/bluetooth/bpa10x.c
new file mode 100644
index 000000000..e63d1af25
--- /dev/null
+++ b/drivers/bluetooth/bpa10x.c
@@ -0,0 +1,451 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *
+ *  Digianswer Bluetooth USB driver
+ *
+ *  Copyright (C) 2004-2007  Marcel Holtmann <marcel@holtmann.org>
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+#include <linux/sched.h>
+#include <linux/errno.h>
+#include <linux/skbuff.h>
+
+#include <linux/usb.h>
+
+#include <net/bluetooth/bluetooth.h>
+#include <net/bluetooth/hci_core.h>
+
+#include "hci_uart.h"
+
+#define VERSION "0.11"
+
+static const struct usb_device_id bpa10x_table[] = {
+	/* Tektronix BPA 100/105 (Digianswer) */
+	{ USB_DEVICE(0x08fd, 0x0002) },
+
+	{ }	/* Terminating entry */
+};
+
+MODULE_DEVICE_TABLE(usb, bpa10x_table);
+
+struct bpa10x_data {
+	struct hci_dev    *hdev;
+	struct usb_device *udev;
+
+	struct usb_anchor tx_anchor;
+	struct usb_anchor rx_anchor;
+
+	struct sk_buff *rx_skb[2];
+	struct hci_uart hu;
+};
+
+static void bpa10x_tx_complete(struct urb *urb)
+{
+	struct sk_buff *skb = urb->context;
+	struct hci_dev *hdev = (struct hci_dev *) skb->dev;
+
+	BT_DBG("%s urb %p status %d count %d", hdev->name,
+					urb, urb->status, urb->actual_length);
+
+	if (!test_bit(HCI_RUNNING, &hdev->flags))
+		goto done;
+
+	if (!urb->status)
+		hdev->stat.byte_tx += urb->transfer_buffer_length;
+	else
+		hdev->stat.err_tx++;
+
+done:
+	kfree(urb->setup_packet);
+
+	kfree_skb(skb);
+}
+
+#define HCI_VENDOR_HDR_SIZE 5
+
+#define HCI_RECV_VENDOR \
+	.type = HCI_VENDOR_PKT, \
+	.hlen = HCI_VENDOR_HDR_SIZE, \
+	.loff = 3, \
+	.lsize = 2, \
+	.maxlen = HCI_MAX_FRAME_SIZE
+
+static const struct h4_recv_pkt bpa10x_recv_pkts[] = {
+	{ H4_RECV_ACL,     .recv = hci_recv_frame },
+	{ H4_RECV_SCO,     .recv = hci_recv_frame },
+	{ H4_RECV_EVENT,   .recv = hci_recv_frame },
+	{ HCI_RECV_VENDOR, .recv = hci_recv_diag  },
+};
+
+static void bpa10x_rx_complete(struct urb *urb)
+{
+	struct hci_dev *hdev = urb->context;
+	struct bpa10x_data *data = hci_get_drvdata(hdev);
+	int err;
+
+	BT_DBG("%s urb %p status %d count %d", hdev->name,
+					urb, urb->status, urb->actual_length);
+
+	if (!test_bit(HCI_RUNNING, &hdev->flags))
+		return;
+
+	if (urb->status == 0) {
+		bool idx = usb_pipebulk(urb->pipe);
+
+		data->rx_skb[idx] = h4_recv_buf(&data->hu, data->rx_skb[idx],
+						urb->transfer_buffer,
+						urb->actual_length,
+						bpa10x_recv_pkts,
+						ARRAY_SIZE(bpa10x_recv_pkts));
+		if (IS_ERR(data->rx_skb[idx])) {
+			bt_dev_err(hdev, "corrupted event packet");
+			hdev->stat.err_rx++;
+			data->rx_skb[idx] = NULL;
+		}
+	}
+
+	usb_anchor_urb(urb, &data->rx_anchor);
+
+	err = usb_submit_urb(urb, GFP_ATOMIC);
+	if (err < 0) {
+		bt_dev_err(hdev, "urb %p failed to resubmit (%d)", urb, -err);
+		usb_unanchor_urb(urb);
+	}
+}
+
+static inline int bpa10x_submit_intr_urb(struct hci_dev *hdev)
+{
+	struct bpa10x_data *data = hci_get_drvdata(hdev);
+	struct urb *urb;
+	unsigned char *buf;
+	unsigned int pipe;
+	int err, size = 16;
+
+	BT_DBG("%s", hdev->name);
+
+	urb = usb_alloc_urb(0, GFP_KERNEL);
+	if (!urb)
+		return -ENOMEM;
+
+	buf = kmalloc(size, GFP_KERNEL);
+	if (!buf) {
+		usb_free_urb(urb);
+		return -ENOMEM;
+	}
+
+	pipe = usb_rcvintpipe(data->udev, 0x81);
+
+	usb_fill_int_urb(urb, data->udev, pipe, buf, size,
+						bpa10x_rx_complete, hdev, 1);
+
+	urb->transfer_flags |= URB_FREE_BUFFER;
+
+	usb_anchor_urb(urb, &data->rx_anchor);
+
+	err = usb_submit_urb(urb, GFP_KERNEL);
+	if (err < 0) {
+		bt_dev_err(hdev, "urb %p submission failed (%d)", urb, -err);
+		usb_unanchor_urb(urb);
+	}
+
+	usb_free_urb(urb);
+
+	return err;
+}
+
+static inline int bpa10x_submit_bulk_urb(struct hci_dev *hdev)
+{
+	struct bpa10x_data *data = hci_get_drvdata(hdev);
+	struct urb *urb;
+	unsigned char *buf;
+	unsigned int pipe;
+	int err, size = 64;
+
+	BT_DBG("%s", hdev->name);
+
+	urb = usb_alloc_urb(0, GFP_KERNEL);
+	if (!urb)
+		return -ENOMEM;
+
+	buf = kmalloc(size, GFP_KERNEL);
+	if (!buf) {
+		usb_free_urb(urb);
+		return -ENOMEM;
+	}
+
+	pipe = usb_rcvbulkpipe(data->udev, 0x82);
+
+	usb_fill_bulk_urb(urb, data->udev, pipe,
+					buf, size, bpa10x_rx_complete, hdev);
+
+	urb->transfer_flags |= URB_FREE_BUFFER;
+
+	usb_anchor_urb(urb, &data->rx_anchor);
+
+	err = usb_submit_urb(urb, GFP_KERNEL);
+	if (err < 0) {
+		bt_dev_err(hdev, "urb %p submission failed (%d)", urb, -err);
+		usb_unanchor_urb(urb);
+	}
+
+	usb_free_urb(urb);
+
+	return err;
+}
+
+static int bpa10x_open(struct hci_dev *hdev)
+{
+	struct bpa10x_data *data = hci_get_drvdata(hdev);
+	int err;
+
+	BT_DBG("%s", hdev->name);
+
+	err = bpa10x_submit_intr_urb(hdev);
+	if (err < 0)
+		goto error;
+
+	err = bpa10x_submit_bulk_urb(hdev);
+	if (err < 0)
+		goto error;
+
+	return 0;
+
+error:
+	usb_kill_anchored_urbs(&data->rx_anchor);
+
+	return err;
+}
+
+static int bpa10x_close(struct hci_dev *hdev)
+{
+	struct bpa10x_data *data = hci_get_drvdata(hdev);
+
+	BT_DBG("%s", hdev->name);
+
+	usb_kill_anchored_urbs(&data->rx_anchor);
+
+	return 0;
+}
+
+static int bpa10x_flush(struct hci_dev *hdev)
+{
+	struct bpa10x_data *data = hci_get_drvdata(hdev);
+
+	BT_DBG("%s", hdev->name);
+
+	usb_kill_anchored_urbs(&data->tx_anchor);
+
+	return 0;
+}
+
+static int bpa10x_setup(struct hci_dev *hdev)
+{
+	static const u8 req[] = { 0x07 };
+	struct sk_buff *skb;
+
+	BT_DBG("%s", hdev->name);
+
+	/* Read revision string */
+	skb = __hci_cmd_sync(hdev, 0xfc0e, sizeof(req), req, HCI_INIT_TIMEOUT);
+	if (IS_ERR(skb))
+		return PTR_ERR(skb);
+
+	/* Bounded print: the device controls skb->len. */
+	if (skb->len > 1) {
+		int len = skb->len - 1;
+
+		bt_dev_info(hdev, "%.*s", len, (char *)(skb->data + 1));
+		hci_set_fw_info(hdev, "%.*s", len, skb->data + 1);
+	}
+
+	kfree_skb(skb);
+	return 0;
+}
+
+static int bpa10x_send_frame(struct hci_dev *hdev, struct sk_buff *skb)
+{
+	struct bpa10x_data *data = hci_get_drvdata(hdev);
+	struct usb_ctrlrequest *dr;
+	struct urb *urb;
+	unsigned int pipe;
+	int err;
+
+	BT_DBG("%s", hdev->name);
+
+	skb->dev = (void *) hdev;
+
+	urb = usb_alloc_urb(0, GFP_KERNEL);
+	if (!urb)
+		return -ENOMEM;
+
+	/* Prepend skb with frame type */
+	*(u8 *)skb_push(skb, 1) = hci_skb_pkt_type(skb);
+
+	switch (hci_skb_pkt_type(skb)) {
+	case HCI_COMMAND_PKT:
+		dr = kmalloc_obj(*dr);
+		if (!dr) {
+			usb_free_urb(urb);
+			return -ENOMEM;
+		}
+
+		dr->bRequestType = USB_TYPE_VENDOR;
+		dr->bRequest     = 0;
+		dr->wIndex       = 0;
+		dr->wValue       = 0;
+		dr->wLength      = __cpu_to_le16(skb->len);
+
+		pipe = usb_sndctrlpipe(data->udev, 0x00);
+
+		usb_fill_control_urb(urb, data->udev, pipe, (void *) dr,
+				skb->data, skb->len, bpa10x_tx_complete, skb);
+
+		hdev->stat.cmd_tx++;
+		break;
+
+	case HCI_ACLDATA_PKT:
+		pipe = usb_sndbulkpipe(data->udev, 0x02);
+
+		usb_fill_bulk_urb(urb, data->udev, pipe,
+				skb->data, skb->len, bpa10x_tx_complete, skb);
+
+		hdev->stat.acl_tx++;
+		break;
+
+	case HCI_SCODATA_PKT:
+		pipe = usb_sndbulkpipe(data->udev, 0x02);
+
+		usb_fill_bulk_urb(urb, data->udev, pipe,
+				skb->data, skb->len, bpa10x_tx_complete, skb);
+
+		hdev->stat.sco_tx++;
+		break;
+
+	default:
+		usb_free_urb(urb);
+		return -EILSEQ;
+	}
+
+	usb_anchor_urb(urb, &data->tx_anchor);
+
+	err = usb_submit_urb(urb, GFP_KERNEL);
+	if (err < 0) {
+		bt_dev_err(hdev, "urb %p submission failed", urb);
+		kfree(urb->setup_packet);
+		usb_unanchor_urb(urb);
+	}
+
+	usb_free_urb(urb);
+
+	return err;
+}
+
+static int bpa10x_set_diag(struct hci_dev *hdev, bool enable)
+{
+	const u8 req[] = { 0x00, enable };
+	struct sk_buff *skb;
+
+	BT_DBG("%s", hdev->name);
+
+	if (!test_bit(HCI_RUNNING, &hdev->flags))
+		return -ENETDOWN;
+
+	/* Enable sniffer operation */
+	skb = __hci_cmd_sync(hdev, 0xfc0e, sizeof(req), req, HCI_INIT_TIMEOUT);
+	if (IS_ERR(skb))
+		return PTR_ERR(skb);
+
+	kfree_skb(skb);
+	return 0;
+}
+
+static int bpa10x_probe(struct usb_interface *intf,
+			const struct usb_device_id *id)
+{
+	struct bpa10x_data *data;
+	struct hci_dev *hdev;
+	int err;
+
+	BT_DBG("intf %p id %p", intf, id);
+
+	if (intf->cur_altsetting->desc.bInterfaceNumber != 0)
+		return -ENODEV;
+
+	data = devm_kzalloc(&intf->dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->udev = interface_to_usbdev(intf);
+
+	init_usb_anchor(&data->tx_anchor);
+	init_usb_anchor(&data->rx_anchor);
+
+	hdev = hci_alloc_dev();
+	if (!hdev)
+		return -ENOMEM;
+
+	hdev->bus = HCI_USB;
+	hci_set_drvdata(hdev, data);
+
+	data->hdev = hdev;
+	data->hu.hdev = hdev;
+
+	SET_HCIDEV_DEV(hdev, &intf->dev);
+
+	hdev->open     = bpa10x_open;
+	hdev->close    = bpa10x_close;
+	hdev->flush    = bpa10x_flush;
+	hdev->setup    = bpa10x_setup;
+	hdev->send     = bpa10x_send_frame;
+	hdev->set_diag = bpa10x_set_diag;
+
+	hci_set_quirk(hdev, HCI_QUIRK_RESET_ON_CLOSE);
+
+	err = hci_register_dev(hdev);
+	if (err < 0) {
+		hci_free_dev(hdev);
+		return err;
+	}
+
+	usb_set_intfdata(intf, data);
+
+	return 0;
+}
+
+static void bpa10x_disconnect(struct usb_interface *intf)
+{
+	struct bpa10x_data *data = usb_get_intfdata(intf);
+
+	BT_DBG("intf %p", intf);
+
+	if (!data)
+		return;
+
+	usb_set_intfdata(intf, NULL);
+
+	hci_unregister_dev(data->hdev);
+
+	hci_free_dev(data->hdev);
+	kfree_skb(data->rx_skb[0]);
+	kfree_skb(data->rx_skb[1]);
+}
+
+static struct usb_driver bpa10x_driver = {
+	.name		= "bpa10x",
+	.probe		= bpa10x_probe,
+	.disconnect	= bpa10x_disconnect,
+	.id_table	= bpa10x_table,
+	.disable_hub_initiated_lpm = 1,
+};
+
+module_usb_driver(bpa10x_driver);
+
+MODULE_AUTHOR("Marcel Holtmann <marcel@holtmann.org>");
+MODULE_DESCRIPTION("Digianswer Bluetooth USB driver ver " VERSION);
+MODULE_VERSION(VERSION);
+MODULE_LICENSE("GPL");