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, 515 insertions, 0 deletions

diff --git a/drivers/bluetooth/hci_mrvl.c b/drivers/bluetooth/hci_mrvl.c
new file mode 100644
index 000000000..5798a8db0
--- /dev/null
+++ b/drivers/bluetooth/hci_mrvl.c
@@ -0,0 +1,515 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *
+ *  Bluetooth HCI UART driver for marvell devices
+ *
+ *  Copyright (C) 2016  Marvell International Ltd.
+ *  Copyright (C) 2016  Intel Corporation
+ */
+
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/skbuff.h>
+#include <linux/firmware.h>
+#include <linux/module.h>
+#include <linux/tty.h>
+#include <linux/of.h>
+#include <linux/serdev.h>
+
+#include <net/bluetooth/bluetooth.h>
+#include <net/bluetooth/hci_core.h>
+
+#include "hci_uart.h"
+
+#define HCI_FW_REQ_PKT 0xA5
+#define HCI_CHIP_VER_PKT 0xAA
+
+#define MRVL_ACK 0x5A
+#define MRVL_NAK 0xBF
+#define MRVL_RAW_DATA 0x1F
+#define MRVL_SET_BAUDRATE 0xFC09
+
+enum {
+	STATE_CHIP_VER_PENDING,
+	STATE_FW_REQ_PENDING,
+	STATE_FW_LOADED,
+};
+
+struct mrvl_data {
+	struct sk_buff *rx_skb;
+	struct sk_buff_head txq;
+	struct sk_buff_head rawq;
+	unsigned long flags;
+	unsigned int tx_len;
+	u8 id, rev;
+};
+
+struct mrvl_serdev {
+	struct hci_uart hu;
+};
+
+struct hci_mrvl_pkt {
+	__le16 lhs;
+	__le16 rhs;
+} __packed;
+#define HCI_MRVL_PKT_SIZE 4
+
+static int mrvl_open(struct hci_uart *hu)
+{
+	struct mrvl_data *mrvl;
+	int ret;
+
+	BT_DBG("hu %p", hu);
+
+	if (!hci_uart_has_flow_control(hu))
+		return -EOPNOTSUPP;
+
+	mrvl = kzalloc_obj(*mrvl);
+	if (!mrvl)
+		return -ENOMEM;
+
+	skb_queue_head_init(&mrvl->txq);
+	skb_queue_head_init(&mrvl->rawq);
+
+	set_bit(STATE_CHIP_VER_PENDING, &mrvl->flags);
+
+	hu->priv = mrvl;
+
+	if (hu->serdev) {
+		ret = serdev_device_open(hu->serdev);
+		if (ret)
+			goto err;
+	}
+
+	return 0;
+err:
+	kfree(mrvl);
+
+	return ret;
+}
+
+static int mrvl_close(struct hci_uart *hu)
+{
+	struct mrvl_data *mrvl = hu->priv;
+
+	BT_DBG("hu %p", hu);
+
+	if (hu->serdev)
+		serdev_device_close(hu->serdev);
+
+	skb_queue_purge(&mrvl->txq);
+	skb_queue_purge(&mrvl->rawq);
+	kfree_skb(mrvl->rx_skb);
+	kfree(mrvl);
+
+	hu->priv = NULL;
+	return 0;
+}
+
+static int mrvl_flush(struct hci_uart *hu)
+{
+	struct mrvl_data *mrvl = hu->priv;
+
+	BT_DBG("hu %p", hu);
+
+	skb_queue_purge(&mrvl->txq);
+	skb_queue_purge(&mrvl->rawq);
+
+	return 0;
+}
+
+static struct sk_buff *mrvl_dequeue(struct hci_uart *hu)
+{
+	struct mrvl_data *mrvl = hu->priv;
+	struct sk_buff *skb;
+
+	skb = skb_dequeue(&mrvl->txq);
+	if (!skb) {
+		/* Any raw data ? */
+		skb = skb_dequeue(&mrvl->rawq);
+	} else {
+		/* Prepend skb with frame type */
+		memcpy(skb_push(skb, 1), &bt_cb(skb)->pkt_type, 1);
+	}
+
+	return skb;
+}
+
+static int mrvl_enqueue(struct hci_uart *hu, struct sk_buff *skb)
+{
+	struct mrvl_data *mrvl = hu->priv;
+
+	skb_queue_tail(&mrvl->txq, skb);
+	return 0;
+}
+
+static void mrvl_send_ack(struct hci_uart *hu, unsigned char type)
+{
+	struct mrvl_data *mrvl = hu->priv;
+	struct sk_buff *skb;
+
+	/* No H4 payload, only 1 byte header */
+	skb = bt_skb_alloc(0, GFP_ATOMIC);
+	if (!skb) {
+		bt_dev_err(hu->hdev, "Unable to alloc ack/nak packet");
+		return;
+	}
+	hci_skb_pkt_type(skb) = type;
+
+	skb_queue_tail(&mrvl->txq, skb);
+	hci_uart_tx_wakeup(hu);
+}
+
+static int mrvl_recv_fw_req(struct hci_dev *hdev, struct sk_buff *skb)
+{
+	struct hci_mrvl_pkt *pkt = (void *)skb->data;
+	struct hci_uart *hu = hci_get_drvdata(hdev);
+	struct mrvl_data *mrvl = hu->priv;
+	int ret = 0;
+
+	if ((pkt->lhs ^ pkt->rhs) != 0xffff) {
+		bt_dev_err(hdev, "Corrupted mrvl header");
+		mrvl_send_ack(hu, MRVL_NAK);
+		ret = -EINVAL;
+		goto done;
+	}
+	mrvl_send_ack(hu, MRVL_ACK);
+
+	if (!test_bit(STATE_FW_REQ_PENDING, &mrvl->flags)) {
+		bt_dev_err(hdev, "Received unexpected firmware request");
+		ret = -EINVAL;
+		goto done;
+	}
+
+	mrvl->tx_len = le16_to_cpu(pkt->lhs);
+
+	clear_bit(STATE_FW_REQ_PENDING, &mrvl->flags);
+	smp_mb__after_atomic();
+	wake_up_bit(&mrvl->flags, STATE_FW_REQ_PENDING);
+
+done:
+	kfree_skb(skb);
+	return ret;
+}
+
+static int mrvl_recv_chip_ver(struct hci_dev *hdev, struct sk_buff *skb)
+{
+	struct hci_mrvl_pkt *pkt = (void *)skb->data;
+	struct hci_uart *hu = hci_get_drvdata(hdev);
+	struct mrvl_data *mrvl = hu->priv;
+	u16 version = le16_to_cpu(pkt->lhs);
+	int ret = 0;
+
+	if ((pkt->lhs ^ pkt->rhs) != 0xffff) {
+		bt_dev_err(hdev, "Corrupted mrvl header");
+		mrvl_send_ack(hu, MRVL_NAK);
+		ret = -EINVAL;
+		goto done;
+	}
+	mrvl_send_ack(hu, MRVL_ACK);
+
+	if (!test_bit(STATE_CHIP_VER_PENDING, &mrvl->flags)) {
+		bt_dev_err(hdev, "Received unexpected chip version");
+		goto done;
+	}
+
+	mrvl->id = version;
+	mrvl->rev = version >> 8;
+
+	bt_dev_info(hdev, "Controller id = %x, rev = %x", mrvl->id, mrvl->rev);
+
+	clear_bit(STATE_CHIP_VER_PENDING, &mrvl->flags);
+	smp_mb__after_atomic();
+	wake_up_bit(&mrvl->flags, STATE_CHIP_VER_PENDING);
+
+done:
+	kfree_skb(skb);
+	return ret;
+}
+
+#define HCI_RECV_CHIP_VER \
+	.type = HCI_CHIP_VER_PKT, \
+	.hlen = HCI_MRVL_PKT_SIZE, \
+	.loff = 0, \
+	.lsize = 0, \
+	.maxlen = HCI_MRVL_PKT_SIZE
+
+#define HCI_RECV_FW_REQ \
+	.type = HCI_FW_REQ_PKT, \
+	.hlen = HCI_MRVL_PKT_SIZE, \
+	.loff = 0, \
+	.lsize = 0, \
+	.maxlen = HCI_MRVL_PKT_SIZE
+
+static const struct h4_recv_pkt mrvl_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_FW_REQ,   .recv = mrvl_recv_fw_req   },
+	{ HCI_RECV_CHIP_VER, .recv = mrvl_recv_chip_ver },
+};
+
+static int mrvl_recv(struct hci_uart *hu, const void *data, int count)
+{
+	struct mrvl_data *mrvl = hu->priv;
+
+	if (!test_bit(HCI_UART_REGISTERED, &hu->flags))
+		return -EUNATCH;
+
+	/* We might receive some noise when there is no firmware loaded. Therefore,
+	 * we drop data if the firmware is not loaded yet and if there is no fw load
+	 * request pending.
+	 */
+	if (!test_bit(STATE_FW_REQ_PENDING, &mrvl->flags) &&
+				!test_bit(STATE_FW_LOADED, &mrvl->flags))
+		return count;
+
+	mrvl->rx_skb = h4_recv_buf(hu, mrvl->rx_skb, data, count,
+				   mrvl_recv_pkts,
+				   ARRAY_SIZE(mrvl_recv_pkts));
+	if (IS_ERR(mrvl->rx_skb)) {
+		int err = PTR_ERR(mrvl->rx_skb);
+		bt_dev_err(hu->hdev, "Frame reassembly failed (%d)", err);
+		mrvl->rx_skb = NULL;
+		return err;
+	}
+
+	return count;
+}
+
+static int mrvl_load_firmware(struct hci_dev *hdev, const char *name)
+{
+	struct hci_uart *hu = hci_get_drvdata(hdev);
+	struct mrvl_data *mrvl = hu->priv;
+	const struct firmware *fw = NULL;
+	const u8 *fw_ptr, *fw_max;
+	int err;
+
+	err = request_firmware(&fw, name, &hdev->dev);
+	if (err < 0) {
+		bt_dev_err(hdev, "Failed to load firmware file %s", name);
+		return err;
+	}
+
+	fw_ptr = fw->data;
+	fw_max = fw->data + fw->size;
+
+	bt_dev_info(hdev, "Loading %s", name);
+
+	set_bit(STATE_FW_REQ_PENDING, &mrvl->flags);
+
+	while (fw_ptr <= fw_max) {
+		struct sk_buff *skb;
+
+		/* Controller drives the firmware load by sending firmware
+		 * request packets containing the expected fragment size.
+		 */
+		err = wait_on_bit_timeout(&mrvl->flags, STATE_FW_REQ_PENDING,
+					  TASK_INTERRUPTIBLE,
+					  msecs_to_jiffies(2000));
+		if (err == -EINTR) {
+			bt_dev_err(hdev, "Firmware load interrupted");
+			break;
+		} else if (err) {
+			bt_dev_err(hdev, "Firmware request timeout");
+			err = -ETIMEDOUT;
+			break;
+		}
+
+		bt_dev_dbg(hdev, "Firmware request, expecting %d bytes",
+			   mrvl->tx_len);
+
+		if (fw_ptr == fw_max) {
+			/* Controller requests a null size once firmware is
+			 * fully loaded. If controller expects more data, there
+			 * is an issue.
+			 */
+			if (!mrvl->tx_len) {
+				bt_dev_info(hdev, "Firmware loading complete");
+			} else {
+				bt_dev_err(hdev, "Firmware loading failure");
+				err = -EINVAL;
+			}
+			break;
+		}
+
+		if (fw_ptr + mrvl->tx_len > fw_max) {
+			mrvl->tx_len = fw_max - fw_ptr;
+			bt_dev_dbg(hdev, "Adjusting tx_len to %d",
+				   mrvl->tx_len);
+		}
+
+		skb = bt_skb_alloc(mrvl->tx_len, GFP_KERNEL);
+		if (!skb) {
+			bt_dev_err(hdev, "Failed to alloc mem for FW packet");
+			err = -ENOMEM;
+			break;
+		}
+		bt_cb(skb)->pkt_type = MRVL_RAW_DATA;
+
+		skb_put_data(skb, fw_ptr, mrvl->tx_len);
+		fw_ptr += mrvl->tx_len;
+
+		set_bit(STATE_FW_REQ_PENDING, &mrvl->flags);
+
+		skb_queue_tail(&mrvl->rawq, skb);
+		hci_uart_tx_wakeup(hu);
+	}
+
+	release_firmware(fw);
+	return err;
+}
+
+static int mrvl_setup(struct hci_uart *hu)
+{
+	int err;
+	struct mrvl_data *mrvl = hu->priv;
+
+	hci_uart_set_flow_control(hu, true);
+
+	err = mrvl_load_firmware(hu->hdev, "mrvl/helper_uart_3000000.bin");
+	if (err) {
+		bt_dev_err(hu->hdev, "Unable to download firmware helper");
+		return -EINVAL;
+	}
+
+	/* Let the final ack go out before switching the baudrate */
+	hci_uart_wait_until_sent(hu);
+
+	if (hu->serdev)
+		serdev_device_set_baudrate(hu->serdev, hu->oper_speed);
+	else
+		hci_uart_set_baudrate(hu, hu->oper_speed);
+
+	hci_uart_set_flow_control(hu, false);
+
+	err = mrvl_load_firmware(hu->hdev, "mrvl/uart8897_bt.bin");
+	if (err)
+		return err;
+
+	set_bit(STATE_FW_LOADED, &mrvl->flags);
+
+	return 0;
+}
+
+static int mrvl_set_baudrate(struct hci_uart *hu, unsigned int speed)
+{
+	int err;
+	struct mrvl_data *mrvl = hu->priv;
+	__le32 speed_le = cpu_to_le32(speed);
+
+	/* The firmware might be loaded by the Wifi driver over SDIO. We wait
+	 * up to 10s for the CTS to go up. Afterward, we know that the firmware
+	 * is ready.
+	 */
+	err = serdev_device_wait_for_cts(hu->serdev, true, 10000);
+	if (err) {
+		bt_dev_err(hu->hdev, "Wait for CTS failed with %d\n", err);
+		return err;
+	}
+
+	set_bit(STATE_FW_LOADED, &mrvl->flags);
+
+	err = __hci_cmd_sync_status(hu->hdev, MRVL_SET_BAUDRATE,
+				    sizeof(speed_le), &speed_le,
+				    HCI_INIT_TIMEOUT);
+	if (err) {
+		bt_dev_err(hu->hdev, "send command failed: %d", err);
+		return err;
+	}
+
+	serdev_device_set_baudrate(hu->serdev, speed);
+
+	/* We forcefully have to send a command to the bluetooth module so that
+	 * the driver detects it after a baudrate change. This is foreseen by
+	 * hci_serdev by setting HCI_UART_VND_DETECT which then causes a dummy
+	 * local version read.
+	 */
+	set_bit(HCI_UART_VND_DETECT, &hu->hdev_flags);
+
+	return 0;
+}
+
+static const struct hci_uart_proto mrvl_proto_8897 = {
+	.id		= HCI_UART_MRVL,
+	.name		= "Marvell",
+	.init_speed	= 115200,
+	.oper_speed	= 3000000,
+	.open		= mrvl_open,
+	.close		= mrvl_close,
+	.flush		= mrvl_flush,
+	.setup		= mrvl_setup,
+	.recv		= mrvl_recv,
+	.enqueue	= mrvl_enqueue,
+	.dequeue	= mrvl_dequeue,
+};
+
+static const struct hci_uart_proto mrvl_proto_8997 = {
+	.id		= HCI_UART_MRVL,
+	.name		= "Marvell 8997",
+	.init_speed	= 115200,
+	.oper_speed	= 3000000,
+	.open		= mrvl_open,
+	.close		= mrvl_close,
+	.flush		= mrvl_flush,
+	.set_baudrate   = mrvl_set_baudrate,
+	.recv		= mrvl_recv,
+	.enqueue	= mrvl_enqueue,
+	.dequeue	= mrvl_dequeue,
+};
+
+static int mrvl_serdev_probe(struct serdev_device *serdev)
+{
+	struct mrvl_serdev *mrvldev;
+	const struct hci_uart_proto *mrvl_proto = device_get_match_data(&serdev->dev);
+
+	mrvldev = devm_kzalloc(&serdev->dev, sizeof(*mrvldev), GFP_KERNEL);
+	if (!mrvldev)
+		return -ENOMEM;
+
+	mrvldev->hu.oper_speed = mrvl_proto->oper_speed;
+	if (mrvl_proto->set_baudrate)
+		of_property_read_u32(serdev->dev.of_node, "max-speed", &mrvldev->hu.oper_speed);
+
+	mrvldev->hu.serdev = serdev;
+	serdev_device_set_drvdata(serdev, mrvldev);
+
+	return hci_uart_register_device(&mrvldev->hu, mrvl_proto);
+}
+
+static void mrvl_serdev_remove(struct serdev_device *serdev)
+{
+	struct mrvl_serdev *mrvldev = serdev_device_get_drvdata(serdev);
+
+	hci_uart_unregister_device(&mrvldev->hu);
+}
+
+static const struct of_device_id __maybe_unused mrvl_bluetooth_of_match[] = {
+	{ .compatible = "mrvl,88w8897", .data = &mrvl_proto_8897},
+	{ .compatible = "mrvl,88w8997", .data = &mrvl_proto_8997},
+	{ },
+};
+MODULE_DEVICE_TABLE(of, mrvl_bluetooth_of_match);
+
+static struct serdev_device_driver mrvl_serdev_driver = {
+	.probe = mrvl_serdev_probe,
+	.remove = mrvl_serdev_remove,
+	.driver = {
+		.name = "hci_uart_mrvl",
+		.of_match_table = of_match_ptr(mrvl_bluetooth_of_match),
+	},
+};
+
+int __init mrvl_init(void)
+{
+	serdev_device_driver_register(&mrvl_serdev_driver);
+
+	return hci_uart_register_proto(&mrvl_proto_8897);
+}
+
+int __exit mrvl_deinit(void)
+{
+	serdev_device_driver_unregister(&mrvl_serdev_driver);
+
+	return hci_uart_unregister_proto(&mrvl_proto_8897);
+}