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, 375 insertions, 0 deletions

diff --git a/drivers/bluetooth/btsdio.c b/drivers/bluetooth/btsdio.c
new file mode 100644
index 000000000..8325655ce
--- /dev/null
+++ b/drivers/bluetooth/btsdio.c
@@ -0,0 +1,375 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *
+ *  Generic Bluetooth SDIO driver
+ *
+ *  Copyright (C) 2007  Cambridge Silicon Radio Ltd.
+ *  Copyright (C) 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/mmc/host.h>
+#include <linux/mmc/sdio_ids.h>
+#include <linux/mmc/sdio_func.h>
+
+#include <net/bluetooth/bluetooth.h>
+#include <net/bluetooth/hci_core.h>
+
+#define VERSION "0.1"
+
+static const struct sdio_device_id btsdio_table[] = {
+	/* Generic Bluetooth Type-A SDIO device */
+	{ SDIO_DEVICE_CLASS(SDIO_CLASS_BT_A) },
+
+	/* Generic Bluetooth Type-B SDIO device */
+	{ SDIO_DEVICE_CLASS(SDIO_CLASS_BT_B) },
+
+	{ }	/* Terminating entry */
+};
+
+MODULE_DEVICE_TABLE(sdio, btsdio_table);
+
+struct btsdio_data {
+	struct hci_dev   *hdev;
+	struct sdio_func *func;
+
+	struct work_struct work;
+
+	struct sk_buff_head txq;
+};
+
+#define REG_RDAT     0x00	/* Receiver Data */
+#define REG_TDAT     0x00	/* Transmitter Data */
+#define REG_PC_RRT   0x10	/* Read Packet Control */
+#define REG_PC_WRT   0x11	/* Write Packet Control */
+#define REG_RTC_STAT 0x12	/* Retry Control Status */
+#define REG_RTC_SET  0x12	/* Retry Control Set */
+#define REG_INTRD    0x13	/* Interrupt Indication */
+#define REG_CL_INTRD 0x13	/* Interrupt Clear */
+#define REG_EN_INTRD 0x14	/* Interrupt Enable */
+#define REG_MD_STAT  0x20	/* Bluetooth Mode Status */
+#define REG_MD_SET   0x20	/* Bluetooth Mode Set */
+
+static int btsdio_tx_packet(struct btsdio_data *data, struct sk_buff *skb)
+{
+	int err;
+
+	BT_DBG("%s", data->hdev->name);
+
+	/* Prepend Type-A header */
+	skb_push(skb, 4);
+	skb->data[0] = (skb->len & 0x0000ff);
+	skb->data[1] = (skb->len & 0x00ff00) >> 8;
+	skb->data[2] = (skb->len & 0xff0000) >> 16;
+	skb->data[3] = hci_skb_pkt_type(skb);
+
+	err = sdio_writesb(data->func, REG_TDAT, skb->data, skb->len);
+	if (err < 0) {
+		skb_pull(skb, 4);
+		sdio_writeb(data->func, 0x01, REG_PC_WRT, NULL);
+		return err;
+	}
+
+	data->hdev->stat.byte_tx += skb->len;
+
+	kfree_skb(skb);
+
+	return 0;
+}
+
+static void btsdio_work(struct work_struct *work)
+{
+	struct btsdio_data *data = container_of(work, struct btsdio_data, work);
+	struct sk_buff *skb;
+	int err;
+
+	BT_DBG("%s", data->hdev->name);
+
+	sdio_claim_host(data->func);
+
+	while ((skb = skb_dequeue(&data->txq))) {
+		err = btsdio_tx_packet(data, skb);
+		if (err < 0) {
+			data->hdev->stat.err_tx++;
+			skb_queue_head(&data->txq, skb);
+			break;
+		}
+	}
+
+	sdio_release_host(data->func);
+}
+
+static int btsdio_rx_packet(struct btsdio_data *data)
+{
+	u8 hdr[4] __attribute__ ((aligned(4)));
+	struct sk_buff *skb;
+	int err, len;
+
+	BT_DBG("%s", data->hdev->name);
+
+	err = sdio_readsb(data->func, hdr, REG_RDAT, 4);
+	if (err < 0)
+		return err;
+
+	len = hdr[0] | (hdr[1] << 8) | (hdr[2] << 16);
+	if (len < 4 || len > 65543)
+		return -EILSEQ;
+
+	skb = bt_skb_alloc(len - 4, GFP_KERNEL);
+	if (!skb) {
+		/* Out of memory. Prepare a read retry and just
+		 * return with the expectation that the next time
+		 * we're called we'll have more memory.
+		 */
+		return -ENOMEM;
+	}
+
+	skb_put(skb, len - 4);
+
+	err = sdio_readsb(data->func, skb->data, REG_RDAT, len - 4);
+	if (err < 0) {
+		kfree_skb(skb);
+		return err;
+	}
+
+	data->hdev->stat.byte_rx += len;
+
+	switch (hdr[3]) {
+	case HCI_EVENT_PKT:
+	case HCI_ACLDATA_PKT:
+	case HCI_SCODATA_PKT:
+	case HCI_ISODATA_PKT:
+		hci_skb_pkt_type(skb) = hdr[3];
+		err = hci_recv_frame(data->hdev, skb);
+		if (err < 0)
+			return err;
+		break;
+	default:
+		kfree_skb(skb);
+		return -EINVAL;
+	}
+
+	sdio_writeb(data->func, 0x00, REG_PC_RRT, NULL);
+
+	return 0;
+}
+
+static void btsdio_interrupt(struct sdio_func *func)
+{
+	struct btsdio_data *data = sdio_get_drvdata(func);
+	int intrd;
+
+	BT_DBG("%s", data->hdev->name);
+
+	intrd = sdio_readb(func, REG_INTRD, NULL);
+	if (intrd & 0x01) {
+		sdio_writeb(func, 0x01, REG_CL_INTRD, NULL);
+
+		if (btsdio_rx_packet(data) < 0) {
+			data->hdev->stat.err_rx++;
+			sdio_writeb(data->func, 0x01, REG_PC_RRT, NULL);
+		}
+	}
+}
+
+static int btsdio_open(struct hci_dev *hdev)
+{
+	struct btsdio_data *data = hci_get_drvdata(hdev);
+	int err;
+
+	BT_DBG("%s", hdev->name);
+
+	sdio_claim_host(data->func);
+
+	err = sdio_enable_func(data->func);
+	if (err < 0)
+		goto release;
+
+	err = sdio_claim_irq(data->func, btsdio_interrupt);
+	if (err < 0) {
+		sdio_disable_func(data->func);
+		goto release;
+	}
+
+	if (data->func->class == SDIO_CLASS_BT_B)
+		sdio_writeb(data->func, 0x00, REG_MD_SET, NULL);
+
+	sdio_writeb(data->func, 0x01, REG_EN_INTRD, NULL);
+
+release:
+	sdio_release_host(data->func);
+
+	return err;
+}
+
+static int btsdio_close(struct hci_dev *hdev)
+{
+	struct btsdio_data *data = hci_get_drvdata(hdev);
+
+	BT_DBG("%s", hdev->name);
+
+	sdio_claim_host(data->func);
+
+	sdio_writeb(data->func, 0x00, REG_EN_INTRD, NULL);
+
+	sdio_release_irq(data->func);
+	sdio_disable_func(data->func);
+
+	sdio_release_host(data->func);
+
+	return 0;
+}
+
+static int btsdio_flush(struct hci_dev *hdev)
+{
+	struct btsdio_data *data = hci_get_drvdata(hdev);
+
+	BT_DBG("%s", hdev->name);
+
+	skb_queue_purge(&data->txq);
+
+	return 0;
+}
+
+static int btsdio_send_frame(struct hci_dev *hdev, struct sk_buff *skb)
+{
+	struct btsdio_data *data = hci_get_drvdata(hdev);
+
+	BT_DBG("%s", hdev->name);
+
+	switch (hci_skb_pkt_type(skb)) {
+	case HCI_COMMAND_PKT:
+		hdev->stat.cmd_tx++;
+		break;
+
+	case HCI_ACLDATA_PKT:
+		hdev->stat.acl_tx++;
+		break;
+
+	case HCI_SCODATA_PKT:
+		hdev->stat.sco_tx++;
+		break;
+
+	default:
+		return -EILSEQ;
+	}
+
+	skb_queue_tail(&data->txq, skb);
+
+	schedule_work(&data->work);
+
+	return 0;
+}
+
+static int btsdio_probe(struct sdio_func *func,
+				const struct sdio_device_id *id)
+{
+	struct btsdio_data *data;
+	struct hci_dev *hdev;
+	struct sdio_func_tuple *tuple = func->tuples;
+	int err;
+
+	BT_DBG("func %p id %p class 0x%04x", func, id, func->class);
+
+	while (tuple) {
+		BT_DBG("code 0x%x size %d", tuple->code, tuple->size);
+		tuple = tuple->next;
+	}
+
+	/* Broadcom devices soldered onto the PCB (non-removable) use an
+	 * UART connection for Bluetooth, ignore the BT SDIO interface.
+	 */
+	if (func->vendor == SDIO_VENDOR_ID_BROADCOM &&
+	    !mmc_card_is_removable(func->card->host)) {
+		switch (func->device) {
+		case SDIO_DEVICE_ID_BROADCOM_43341:
+		case SDIO_DEVICE_ID_BROADCOM_43430:
+		case SDIO_DEVICE_ID_BROADCOM_4345:
+		case SDIO_DEVICE_ID_BROADCOM_43455:
+		case SDIO_DEVICE_ID_BROADCOM_4356:
+		case SDIO_DEVICE_ID_BROADCOM_CYPRESS_4373:
+			return -ENODEV;
+		}
+	}
+
+	data = devm_kzalloc(&func->dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->func = func;
+
+	INIT_WORK(&data->work, btsdio_work);
+
+	skb_queue_head_init(&data->txq);
+
+	hdev = hci_alloc_dev();
+	if (!hdev)
+		return -ENOMEM;
+
+	hdev->bus = HCI_SDIO;
+	hci_set_drvdata(hdev, data);
+
+	data->hdev = hdev;
+
+	SET_HCIDEV_DEV(hdev, &func->dev);
+
+	hdev->open     = btsdio_open;
+	hdev->close    = btsdio_close;
+	hdev->flush    = btsdio_flush;
+	hdev->send     = btsdio_send_frame;
+
+	if (func->vendor == 0x0104 && func->device == 0x00c5)
+		hci_set_quirk(hdev, HCI_QUIRK_RESET_ON_CLOSE);
+
+	err = hci_register_dev(hdev);
+	if (err < 0) {
+		hci_free_dev(hdev);
+		return err;
+	}
+
+	sdio_set_drvdata(func, data);
+
+	return 0;
+}
+
+static void btsdio_remove(struct sdio_func *func)
+{
+	struct btsdio_data *data = sdio_get_drvdata(func);
+	struct hci_dev *hdev;
+
+	BT_DBG("func %p", func);
+
+	if (!data)
+		return;
+
+	cancel_work_sync(&data->work);
+	hdev = data->hdev;
+
+	sdio_set_drvdata(func, NULL);
+
+	hci_unregister_dev(hdev);
+
+	hci_free_dev(hdev);
+}
+
+static struct sdio_driver btsdio_driver = {
+	.name		= "btsdio",
+	.probe		= btsdio_probe,
+	.remove		= btsdio_remove,
+	.id_table	= btsdio_table,
+};
+
+module_sdio_driver(btsdio_driver);
+
+MODULE_AUTHOR("Marcel Holtmann <marcel@holtmann.org>");
+MODULE_DESCRIPTION("Generic Bluetooth SDIO driver ver " VERSION);
+MODULE_VERSION(VERSION);
+MODULE_LICENSE("GPL");