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, 429 insertions, 0 deletions

diff --git a/drivers/net/usb/ch9200.c b/drivers/net/usb/ch9200.c
new file mode 100644
index 000000000..a206ffa76
--- /dev/null
+++ b/drivers/net/usb/ch9200.c
@@ -0,0 +1,429 @@
+/*
+ * USB 10M/100M ethernet adapter
+ *
+ * This file is licensed under the terms of the GNU General Public License
+ * version 2. This program is licensed "as is" without any warranty of any
+ * kind, whether express or implied
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/stddef.h>
+#include <linux/init.h>
+#include <linux/netdevice.h>
+#include <linux/etherdevice.h>
+#include <linux/ethtool.h>
+#include <linux/mii.h>
+#include <linux/usb.h>
+#include <linux/crc32.h>
+#include <linux/usb/usbnet.h>
+#include <linux/slab.h>
+
+#define CH9200_VID		0x1A86
+#define CH9200_PID_E092		0xE092
+
+#define CTRL_TIMEOUT_MS		1000
+
+#define CONTROL_TIMEOUT_MS 1000
+
+#define REQUEST_READ	0x0E
+#define REQUEST_WRITE	0x0F
+
+/* Address space:
+ * 00-63 : MII
+ * 64-128: MAC
+ *
+ * Note: all accesses must be 16-bit
+ */
+
+#define MAC_REG_CTRL 64
+#define MAC_REG_STATUS 66
+#define MAC_REG_INTERRUPT_MASK 68
+#define MAC_REG_PHY_COMMAND 70
+#define MAC_REG_PHY_DATA 72
+#define MAC_REG_STATION_L 74
+#define MAC_REG_STATION_M 76
+#define MAC_REG_STATION_H 78
+#define MAC_REG_HASH_L 80
+#define MAC_REG_HASH_M1 82
+#define MAC_REG_HASH_M2 84
+#define MAC_REG_HASH_H 86
+#define MAC_REG_THRESHOLD 88
+#define MAC_REG_FIFO_DEPTH 90
+#define MAC_REG_PAUSE 92
+#define MAC_REG_FLOW_CONTROL 94
+
+/* Control register bits
+ *
+ * Note: bits 13 and 15 are reserved
+ */
+#define LOOPBACK		(0x01 << 14)
+#define BASE100X		(0x01 << 12)
+#define MBPS_10			(0x01 << 11)
+#define DUPLEX_MODE		(0x01 << 10)
+#define PAUSE_FRAME		(0x01 << 9)
+#define PROMISCUOUS		(0x01 << 8)
+#define MULTICAST		(0x01 << 7)
+#define BROADCAST		(0x01 << 6)
+#define HASH			(0x01 << 5)
+#define APPEND_PAD		(0x01 << 4)
+#define APPEND_CRC		(0x01 << 3)
+#define TRANSMITTER_ACTION	(0x01 << 2)
+#define RECEIVER_ACTION		(0x01 << 1)
+#define DMA_ACTION		(0x01 << 0)
+
+/* Status register bits
+ *
+ * Note: bits 7-15 are reserved
+ */
+#define ALIGNMENT		(0x01 << 6)
+#define FIFO_OVER_RUN		(0x01 << 5)
+#define FIFO_UNDER_RUN		(0x01 << 4)
+#define RX_ERROR		(0x01 << 3)
+#define RX_COMPLETE		(0x01 << 2)
+#define TX_ERROR		(0x01 << 1)
+#define TX_COMPLETE		(0x01 << 0)
+
+/* FIFO depth register bits
+ *
+ * Note: bits 6 and 14 are reserved
+ */
+
+#define ETH_TXBD		(0x01 << 15)
+#define ETN_TX_FIFO_DEPTH	(0x01 << 8)
+#define ETH_RXBD		(0x01 << 7)
+#define ETH_RX_FIFO_DEPTH	(0x01 << 0)
+
+static int control_read(struct usbnet *dev,
+			unsigned char request, unsigned short value,
+			unsigned short index, void *data, unsigned short size,
+			int timeout)
+{
+	unsigned char *buf = NULL;
+	unsigned char request_type;
+	int err = 0;
+
+	if (request == REQUEST_READ)
+		request_type = (USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_OTHER);
+	else
+		request_type = (USB_DIR_IN | USB_TYPE_VENDOR |
+				USB_RECIP_DEVICE);
+
+	netdev_dbg(dev->net, "%s() index=0x%02x size=%d\n",
+		   __func__, index, size);
+
+	buf = kmalloc(size, GFP_KERNEL);
+	if (!buf) {
+		err = -ENOMEM;
+		goto err_out;
+	}
+
+	err = usb_control_msg(dev->udev,
+			      usb_rcvctrlpipe(dev->udev, 0),
+			      request, request_type, value, index, buf, size,
+			      timeout);
+	if (err == size)
+		memcpy(data, buf, size);
+	else if (err >= 0)
+		err = -EINVAL;
+	kfree(buf);
+
+err_out:
+	return err;
+}
+
+static int control_write(struct usbnet *dev, unsigned char request,
+			 unsigned short value, unsigned short index,
+			 void *data, unsigned short size, int timeout)
+{
+	unsigned char *buf = NULL;
+	unsigned char request_type;
+	int err = 0;
+
+	if (request == REQUEST_WRITE)
+		request_type = (USB_DIR_OUT | USB_TYPE_VENDOR |
+				USB_RECIP_OTHER);
+	else
+		request_type = (USB_DIR_OUT | USB_TYPE_VENDOR |
+				USB_RECIP_DEVICE);
+
+	netdev_dbg(dev->net, "%s() index=0x%02x size=%d\n",
+		   __func__, index, size);
+
+	if (data) {
+		buf = kmemdup(data, size, GFP_KERNEL);
+		if (!buf) {
+			err = -ENOMEM;
+			goto err_out;
+		}
+	}
+
+	err = usb_control_msg(dev->udev,
+			      usb_sndctrlpipe(dev->udev, 0),
+			      request, request_type, value, index, buf, size,
+			      timeout);
+	if (err >= 0 && err < size)
+		err = -EINVAL;
+	kfree(buf);
+
+	return 0;
+
+err_out:
+	return err;
+}
+
+static int ch9200_mdio_read(struct net_device *netdev, int phy_id, int loc)
+{
+	struct usbnet *dev = netdev_priv(netdev);
+	unsigned char buff[2];
+	int ret;
+
+	netdev_dbg(netdev, "%s phy_id:%02x loc:%02x\n",
+		   __func__, phy_id, loc);
+
+	if (phy_id != 0)
+		return -ENODEV;
+
+	ret = control_read(dev, REQUEST_READ, 0, loc * 2, buff, 0x02,
+			   CONTROL_TIMEOUT_MS);
+	if (ret < 0)
+		return ret;
+
+	return (buff[0] | buff[1] << 8);
+}
+
+static void ch9200_mdio_write(struct net_device *netdev,
+			      int phy_id, int loc, int val)
+{
+	struct usbnet *dev = netdev_priv(netdev);
+	unsigned char buff[2];
+
+	netdev_dbg(netdev, "%s() phy_id=%02x loc:%02x\n",
+		   __func__, phy_id, loc);
+
+	if (phy_id != 0)
+		return;
+
+	buff[0] = (unsigned char)val;
+	buff[1] = (unsigned char)(val >> 8);
+
+	control_write(dev, REQUEST_WRITE, 0, loc * 2, buff, 0x02,
+		      CONTROL_TIMEOUT_MS);
+}
+
+static int ch9200_link_reset(struct usbnet *dev)
+{
+	struct ethtool_cmd ecmd;
+
+	mii_check_media(&dev->mii, 1, 1);
+	mii_ethtool_gset(&dev->mii, &ecmd);
+
+	netdev_dbg(dev->net, "%s() speed:%d duplex:%d\n",
+		   __func__, ecmd.speed, ecmd.duplex);
+
+	return 0;
+}
+
+static void ch9200_status(struct usbnet *dev, struct urb *urb)
+{
+	int link;
+	unsigned char *buf;
+
+	if (urb->actual_length < 16)
+		return;
+
+	buf = urb->transfer_buffer;
+	link = !!(buf[0] & 0x01);
+
+	if (link) {
+		netif_carrier_on(dev->net);
+		usbnet_defer_kevent(dev, EVENT_LINK_RESET);
+	} else {
+		netif_carrier_off(dev->net);
+	}
+}
+
+static struct sk_buff *ch9200_tx_fixup(struct usbnet *dev, struct sk_buff *skb,
+				       gfp_t flags)
+{
+	int i = 0;
+	int len = 0;
+	int tx_overhead = 0;
+
+	tx_overhead = 0x40;
+
+	len = skb->len;
+	if (skb_cow_head(skb, tx_overhead)) {
+		dev_kfree_skb_any(skb);
+		return NULL;
+	}
+
+	__skb_push(skb, tx_overhead);
+	/* usbnet adds padding if length is a multiple of packet size
+	 * if so, adjust length value in header
+	 */
+	if ((skb->len % dev->maxpacket) == 0)
+		len++;
+
+	skb->data[0] = len;
+	skb->data[1] = len >> 8;
+	skb->data[2] = 0x00;
+	skb->data[3] = 0x80;
+
+	for (i = 4; i < 48; i++)
+		skb->data[i] = 0x00;
+
+	skb->data[48] = len;
+	skb->data[49] = len >> 8;
+	skb->data[50] = 0x00;
+	skb->data[51] = 0x80;
+
+	for (i = 52; i < 64; i++)
+		skb->data[i] = 0x00;
+
+	return skb;
+}
+
+static int ch9200_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
+{
+	int len = 0;
+	int rx_overhead = 0;
+
+	rx_overhead = 64;
+
+	if (unlikely(skb->len < rx_overhead)) {
+		dev_err(&dev->udev->dev, "unexpected tiny rx frame\n");
+		return 0;
+	}
+
+	len = (skb->data[skb->len - 16] | skb->data[skb->len - 15] << 8);
+	skb_trim(skb, len);
+
+	return 1;
+}
+
+static int get_mac_address(struct usbnet *dev, unsigned char *data)
+{
+	int err = 0;
+	unsigned char mac_addr[0x06];
+	int rd_mac_len = 0;
+
+	netdev_dbg(dev->net, "%s:\n\tusbnet VID:%0x PID:%0x\n", __func__,
+		   le16_to_cpu(dev->udev->descriptor.idVendor),
+		   le16_to_cpu(dev->udev->descriptor.idProduct));
+
+	memset(mac_addr, 0, sizeof(mac_addr));
+	rd_mac_len = control_read(dev, REQUEST_READ, 0,
+				  MAC_REG_STATION_L, mac_addr, 0x02,
+				  CONTROL_TIMEOUT_MS);
+	rd_mac_len += control_read(dev, REQUEST_READ, 0, MAC_REG_STATION_M,
+				   mac_addr + 2, 0x02, CONTROL_TIMEOUT_MS);
+	rd_mac_len += control_read(dev, REQUEST_READ, 0, MAC_REG_STATION_H,
+				   mac_addr + 4, 0x02, CONTROL_TIMEOUT_MS);
+	if (rd_mac_len != ETH_ALEN)
+		err = -EINVAL;
+
+	data[0] = mac_addr[5];
+	data[1] = mac_addr[4];
+	data[2] = mac_addr[3];
+	data[3] = mac_addr[2];
+	data[4] = mac_addr[1];
+	data[5] = mac_addr[0];
+
+	return err;
+}
+
+static int ch9200_bind(struct usbnet *dev, struct usb_interface *intf)
+{
+	int retval = 0;
+	unsigned char data[2];
+	u8 addr[ETH_ALEN];
+
+	retval = usbnet_get_endpoints(dev, intf);
+	if (retval)
+		return retval;
+
+	dev->mii.dev = dev->net;
+	dev->mii.mdio_read = ch9200_mdio_read;
+	dev->mii.mdio_write = ch9200_mdio_write;
+	dev->mii.reg_num_mask = 0x1f;
+
+	dev->mii.phy_id_mask = 0x1f;
+
+	dev->hard_mtu = dev->net->mtu + dev->net->hard_header_len;
+	dev->rx_urb_size = 24 * 64 + 16;
+	mii_nway_restart(&dev->mii);
+
+	data[0] = 0x01;
+	data[1] = 0x0F;
+	retval = control_write(dev, REQUEST_WRITE, 0, MAC_REG_THRESHOLD, data,
+			       0x02, CONTROL_TIMEOUT_MS);
+
+	data[0] = 0xA0;
+	data[1] = 0x90;
+	retval = control_write(dev, REQUEST_WRITE, 0, MAC_REG_FIFO_DEPTH, data,
+			       0x02, CONTROL_TIMEOUT_MS);
+
+	data[0] = 0x30;
+	data[1] = 0x00;
+	retval = control_write(dev, REQUEST_WRITE, 0, MAC_REG_PAUSE, data,
+			       0x02, CONTROL_TIMEOUT_MS);
+
+	data[0] = 0x17;
+	data[1] = 0xD8;
+	retval = control_write(dev, REQUEST_WRITE, 0, MAC_REG_FLOW_CONTROL,
+			       data, 0x02, CONTROL_TIMEOUT_MS);
+
+	/* Undocumented register */
+	data[0] = 0x01;
+	data[1] = 0x00;
+	retval = control_write(dev, REQUEST_WRITE, 0, 254, data, 0x02,
+			       CONTROL_TIMEOUT_MS);
+
+	data[0] = 0x5F;
+	data[1] = 0x0D;
+	retval = control_write(dev, REQUEST_WRITE, 0, MAC_REG_CTRL, data, 0x02,
+			       CONTROL_TIMEOUT_MS);
+
+	retval = get_mac_address(dev, addr);
+	eth_hw_addr_set(dev->net, addr);
+
+	return retval;
+}
+
+static const struct driver_info ch9200_info = {
+	.description = "CH9200 USB to Network Adaptor",
+	.flags = FLAG_ETHER,
+	.bind = ch9200_bind,
+	.rx_fixup = ch9200_rx_fixup,
+	.tx_fixup = ch9200_tx_fixup,
+	.status = ch9200_status,
+	.link_reset = ch9200_link_reset,
+	.reset = ch9200_link_reset,
+};
+
+static const struct usb_device_id ch9200_products[] = {
+	{
+	 USB_DEVICE(0x1A86, 0xE092),
+	 .driver_info = (unsigned long)&ch9200_info,
+	 },
+	{},
+};
+
+MODULE_DEVICE_TABLE(usb, ch9200_products);
+
+static struct usb_driver ch9200_driver = {
+	.name = "ch9200",
+	.id_table = ch9200_products,
+	.probe = usbnet_probe,
+	.disconnect = usbnet_disconnect,
+	.suspend = usbnet_suspend,
+	.resume = usbnet_resume,
+};
+
+module_usb_driver(ch9200_driver);
+
+MODULE_DESCRIPTION("QinHeng CH9200 USB Network device");
+MODULE_LICENSE("GPL");