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, 343 insertions, 0 deletions

diff --git a/drivers/i2c/busses/i2c-ljca.c b/drivers/i2c/busses/i2c-ljca.c
new file mode 100644
index 000000000..93274f0c2
--- /dev/null
+++ b/drivers/i2c/busses/i2c-ljca.c
@@ -0,0 +1,343 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Intel La Jolla Cove Adapter USB-I2C driver
+ *
+ * Copyright (c) 2023, Intel Corporation.
+ */
+
+#include <linux/acpi.h>
+#include <linux/auxiliary_bus.h>
+#include <linux/bitfield.h>
+#include <linux/bits.h>
+#include <linux/dev_printk.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/usb/ljca.h>
+
+/* I2C init flags */
+#define LJCA_I2C_INIT_FLAG_MODE			BIT(0)
+#define LJCA_I2C_INIT_FLAG_MODE_POLLING		FIELD_PREP(LJCA_I2C_INIT_FLAG_MODE, 0)
+#define LJCA_I2C_INIT_FLAG_MODE_INTERRUPT	FIELD_PREP(LJCA_I2C_INIT_FLAG_MODE, 1)
+
+#define LJCA_I2C_INIT_FLAG_ADDR_16BIT		BIT(0)
+
+#define LJCA_I2C_INIT_FLAG_FREQ			GENMASK(2, 1)
+#define LJCA_I2C_INIT_FLAG_FREQ_100K		FIELD_PREP(LJCA_I2C_INIT_FLAG_FREQ, 0)
+#define LJCA_I2C_INIT_FLAG_FREQ_400K		FIELD_PREP(LJCA_I2C_INIT_FLAG_FREQ, 1)
+#define LJCA_I2C_INIT_FLAG_FREQ_1M		FIELD_PREP(LJCA_I2C_INIT_FLAG_FREQ, 2)
+
+#define LJCA_I2C_BUF_SIZE			60u
+#define LJCA_I2C_MAX_XFER_SIZE			(LJCA_I2C_BUF_SIZE - sizeof(struct ljca_i2c_rw_packet))
+
+/* I2C commands */
+enum ljca_i2c_cmd {
+	LJCA_I2C_INIT = 1,
+	LJCA_I2C_XFER,
+	LJCA_I2C_START,
+	LJCA_I2C_STOP,
+	LJCA_I2C_READ,
+	LJCA_I2C_WRITE,
+};
+
+enum ljca_xfer_type {
+	LJCA_I2C_WRITE_XFER_TYPE,
+	LJCA_I2C_READ_XFER_TYPE,
+};
+
+/* I2C raw commands: Init/Start/Read/Write/Stop */
+struct ljca_i2c_rw_packet {
+	u8 id;
+	__le16 len;
+	u8 data[] __counted_by(len);
+} __packed;
+
+struct ljca_i2c_dev {
+	struct ljca_client *ljca;
+	struct ljca_i2c_info *i2c_info;
+	struct i2c_adapter adap;
+
+	u8 obuf[LJCA_I2C_BUF_SIZE];
+	u8 ibuf[LJCA_I2C_BUF_SIZE];
+};
+
+static int ljca_i2c_init(struct ljca_i2c_dev *ljca_i2c, u8 id)
+{
+	struct ljca_i2c_rw_packet *w_packet =
+			(struct ljca_i2c_rw_packet *)ljca_i2c->obuf;
+	int ret;
+
+	w_packet->id = id;
+	w_packet->len = cpu_to_le16(sizeof(*w_packet->data));
+	w_packet->data[0] = LJCA_I2C_INIT_FLAG_FREQ_400K;
+
+	ret = ljca_transfer(ljca_i2c->ljca, LJCA_I2C_INIT, (u8 *)w_packet,
+			    struct_size(w_packet, data, 1), NULL, 0);
+
+	return ret < 0 ? ret : 0;
+}
+
+static int ljca_i2c_start(struct ljca_i2c_dev *ljca_i2c, u8 target_addr,
+			  enum ljca_xfer_type type)
+{
+	struct ljca_i2c_rw_packet *w_packet =
+			(struct ljca_i2c_rw_packet *)ljca_i2c->obuf;
+	struct ljca_i2c_rw_packet *r_packet =
+			(struct ljca_i2c_rw_packet *)ljca_i2c->ibuf;
+	s16 rp_len;
+	int ret;
+
+	w_packet->id = ljca_i2c->i2c_info->id;
+	w_packet->len = cpu_to_le16(sizeof(*w_packet->data));
+	w_packet->data[0] = (target_addr << 1) | type;
+
+	ret = ljca_transfer(ljca_i2c->ljca, LJCA_I2C_START, (u8 *)w_packet,
+			    struct_size(w_packet, data, 1), (u8 *)r_packet,
+			    LJCA_I2C_BUF_SIZE);
+	if (ret < 0 || ret < sizeof(*r_packet))
+		return ret < 0 ? ret : -EIO;
+
+	rp_len = le16_to_cpu(r_packet->len);
+	if (rp_len < 0 || r_packet->id != w_packet->id) {
+		dev_dbg(&ljca_i2c->adap.dev,
+			"i2c start failed len: %d id: %d %d\n",
+			rp_len, r_packet->id, w_packet->id);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+static void ljca_i2c_stop(struct ljca_i2c_dev *ljca_i2c)
+{
+	struct ljca_i2c_rw_packet *w_packet =
+			(struct ljca_i2c_rw_packet *)ljca_i2c->obuf;
+	struct ljca_i2c_rw_packet *r_packet =
+			(struct ljca_i2c_rw_packet *)ljca_i2c->ibuf;
+	s16 rp_len;
+	int ret;
+
+	w_packet->id = ljca_i2c->i2c_info->id;
+	w_packet->len = cpu_to_le16(sizeof(*w_packet->data));
+	w_packet->data[0] = 0;
+
+	ret = ljca_transfer(ljca_i2c->ljca, LJCA_I2C_STOP, (u8 *)w_packet,
+			    struct_size(w_packet, data, 1), (u8 *)r_packet,
+			    LJCA_I2C_BUF_SIZE);
+	if (ret < 0 || ret < sizeof(*r_packet)) {
+		dev_dbg(&ljca_i2c->adap.dev,
+			"i2c stop failed ret: %d id: %d\n",
+			ret, w_packet->id);
+		return;
+	}
+
+	rp_len = le16_to_cpu(r_packet->len);
+	if (rp_len < 0 || r_packet->id != w_packet->id)
+		dev_dbg(&ljca_i2c->adap.dev,
+			"i2c stop failed len: %d id: %d %d\n",
+			rp_len, r_packet->id, w_packet->id);
+}
+
+static int ljca_i2c_pure_read(struct ljca_i2c_dev *ljca_i2c, u8 *data, u8 len)
+{
+	struct ljca_i2c_rw_packet *w_packet =
+			(struct ljca_i2c_rw_packet *)ljca_i2c->obuf;
+	struct ljca_i2c_rw_packet *r_packet =
+			(struct ljca_i2c_rw_packet *)ljca_i2c->ibuf;
+	s16 rp_len;
+	int ret;
+
+	w_packet->id = ljca_i2c->i2c_info->id;
+	w_packet->len = cpu_to_le16(len);
+	w_packet->data[0] = 0;
+
+	ret = ljca_transfer(ljca_i2c->ljca, LJCA_I2C_READ, (u8 *)w_packet,
+			    struct_size(w_packet, data, 1), (u8 *)r_packet,
+			    LJCA_I2C_BUF_SIZE);
+	if (ret < 0 || ret < sizeof(*r_packet))
+		return ret < 0 ? ret : -EIO;
+
+	rp_len = le16_to_cpu(r_packet->len);
+	if (rp_len != len || r_packet->id != w_packet->id) {
+		dev_dbg(&ljca_i2c->adap.dev,
+			"i2c raw read failed len: %d id: %d %d\n",
+			rp_len, r_packet->id, w_packet->id);
+		return -EIO;
+	}
+
+	memcpy(data, r_packet->data, len);
+
+	return 0;
+}
+
+static int ljca_i2c_read(struct ljca_i2c_dev *ljca_i2c, u8 target_addr, u8 *data,
+			 u8 len)
+{
+	int ret;
+
+	ret = ljca_i2c_start(ljca_i2c, target_addr, LJCA_I2C_READ_XFER_TYPE);
+	if (!ret)
+		ret = ljca_i2c_pure_read(ljca_i2c, data, len);
+
+	ljca_i2c_stop(ljca_i2c);
+
+	return ret;
+}
+
+static int ljca_i2c_pure_write(struct ljca_i2c_dev *ljca_i2c, u8 *data, u8 len)
+{
+	struct ljca_i2c_rw_packet *w_packet =
+			(struct ljca_i2c_rw_packet *)ljca_i2c->obuf;
+	struct ljca_i2c_rw_packet *r_packet =
+			(struct ljca_i2c_rw_packet *)ljca_i2c->ibuf;
+	s16 rplen;
+	int ret;
+
+	w_packet->id = ljca_i2c->i2c_info->id;
+	w_packet->len = cpu_to_le16(len);
+	memcpy(w_packet->data, data, len);
+
+	ret = ljca_transfer(ljca_i2c->ljca, LJCA_I2C_WRITE, (u8 *)w_packet,
+			    struct_size(w_packet, data, len), (u8 *)r_packet,
+			    LJCA_I2C_BUF_SIZE);
+	if (ret < 0 || ret < sizeof(*r_packet))
+		return ret < 0 ? ret : -EIO;
+
+	rplen = le16_to_cpu(r_packet->len);
+	if (rplen != len || r_packet->id != w_packet->id) {
+		dev_dbg(&ljca_i2c->adap.dev,
+			"i2c write failed len: %d id: %d/%d\n",
+			rplen, r_packet->id, w_packet->id);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+static int ljca_i2c_write(struct ljca_i2c_dev *ljca_i2c, u8 target_addr,
+			  u8 *data, u8 len)
+{
+	int ret;
+
+	ret = ljca_i2c_start(ljca_i2c, target_addr, LJCA_I2C_WRITE_XFER_TYPE);
+	if (!ret)
+		ret = ljca_i2c_pure_write(ljca_i2c, data, len);
+
+	ljca_i2c_stop(ljca_i2c);
+
+	return ret;
+}
+
+static int ljca_i2c_xfer(struct i2c_adapter *adapter, struct i2c_msg *msg,
+			 int num)
+{
+	struct ljca_i2c_dev *ljca_i2c;
+	struct i2c_msg *cur_msg;
+	int i, ret;
+
+	ljca_i2c = i2c_get_adapdata(adapter);
+	if (!ljca_i2c)
+		return -EINVAL;
+
+	for (i = 0; i < num; i++) {
+		cur_msg = &msg[i];
+		if (cur_msg->flags & I2C_M_RD)
+			ret = ljca_i2c_read(ljca_i2c, cur_msg->addr,
+					    cur_msg->buf, cur_msg->len);
+		else
+			ret = ljca_i2c_write(ljca_i2c, cur_msg->addr,
+					     cur_msg->buf, cur_msg->len);
+
+		if (ret)
+			return ret;
+	}
+
+	return num;
+}
+
+static u32 ljca_i2c_func(struct i2c_adapter *adap)
+{
+	return I2C_FUNC_I2C | (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK);
+}
+
+static const struct i2c_adapter_quirks ljca_i2c_quirks = {
+	.flags = I2C_AQ_NO_ZERO_LEN,
+	.max_read_len = LJCA_I2C_MAX_XFER_SIZE,
+	.max_write_len = LJCA_I2C_MAX_XFER_SIZE,
+};
+
+static const struct i2c_algorithm ljca_i2c_algo = {
+	.xfer = ljca_i2c_xfer,
+	.functionality = ljca_i2c_func,
+};
+
+static int ljca_i2c_probe(struct auxiliary_device *auxdev,
+			  const struct auxiliary_device_id *aux_dev_id)
+{
+	struct ljca_client *ljca = auxiliary_dev_to_ljca_client(auxdev);
+	struct ljca_i2c_dev *ljca_i2c;
+	int ret;
+
+	ljca_i2c = devm_kzalloc(&auxdev->dev, sizeof(*ljca_i2c), GFP_KERNEL);
+	if (!ljca_i2c)
+		return -ENOMEM;
+
+	ljca_i2c->ljca = ljca;
+	ljca_i2c->i2c_info = dev_get_platdata(&auxdev->dev);
+
+	ljca_i2c->adap.owner = THIS_MODULE;
+	ljca_i2c->adap.class = I2C_CLASS_HWMON;
+	ljca_i2c->adap.algo = &ljca_i2c_algo;
+	ljca_i2c->adap.quirks = &ljca_i2c_quirks;
+	ljca_i2c->adap.dev.parent = &auxdev->dev;
+
+	snprintf(ljca_i2c->adap.name, sizeof(ljca_i2c->adap.name), "%s-%s-%d",
+		 dev_name(&auxdev->dev), dev_name(auxdev->dev.parent),
+		 ljca_i2c->i2c_info->id);
+
+	device_set_node(&ljca_i2c->adap.dev, dev_fwnode(&auxdev->dev));
+
+	i2c_set_adapdata(&ljca_i2c->adap, ljca_i2c);
+	auxiliary_set_drvdata(auxdev, ljca_i2c);
+
+	ret = ljca_i2c_init(ljca_i2c, ljca_i2c->i2c_info->id);
+	if (ret)
+		return dev_err_probe(&auxdev->dev, -EIO,
+				     "i2c init failed id: %d\n",
+				     ljca_i2c->i2c_info->id);
+
+	ret = devm_i2c_add_adapter(&auxdev->dev, &ljca_i2c->adap);
+	if (ret)
+		return ret;
+
+	if (has_acpi_companion(&ljca_i2c->adap.dev))
+		acpi_dev_clear_dependencies(ACPI_COMPANION(&ljca_i2c->adap.dev));
+
+	return 0;
+}
+
+static void ljca_i2c_remove(struct auxiliary_device *auxdev)
+{
+	struct ljca_i2c_dev *ljca_i2c = auxiliary_get_drvdata(auxdev);
+
+	i2c_del_adapter(&ljca_i2c->adap);
+}
+
+static const struct auxiliary_device_id ljca_i2c_id_table[] = {
+	{ "usb_ljca.ljca-i2c", 0 },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(auxiliary, ljca_i2c_id_table);
+
+static struct auxiliary_driver ljca_i2c_driver = {
+	.probe = ljca_i2c_probe,
+	.remove = ljca_i2c_remove,
+	.id_table = ljca_i2c_id_table,
+};
+module_auxiliary_driver(ljca_i2c_driver);
+
+MODULE_AUTHOR("Wentong Wu <wentong.wu@intel.com>");
+MODULE_AUTHOR("Zhifeng Wang <zhifeng.wang@intel.com>");
+MODULE_AUTHOR("Lixu Zhang <lixu.zhang@intel.com>");
+MODULE_DESCRIPTION("Intel La Jolla Cove Adapter USB-I2C driver");
+MODULE_LICENSE("GPL");
+MODULE_IMPORT_NS("LJCA");