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, 163 insertions, 0 deletions

diff --git a/drivers/usb/misc/usb4604.c b/drivers/usb/misc/usb4604.c
new file mode 100644
index 000000000..2ae965671
--- /dev/null
+++ b/drivers/usb/misc/usb4604.c
@@ -0,0 +1,163 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Driver for SMSC USB4604 USB HSIC 4-port 2.0 hub controller driver
+ * Based on usb3503 driver
+ *
+ * Copyright (c) 2012-2013 Dongjin Kim (tobetter@gmail.com)
+ * Copyright (c) 2016 Linaro Ltd.
+ */
+
+#include <linux/i2c.h>
+#include <linux/delay.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/gpio/consumer.h>
+
+enum usb4604_mode {
+	USB4604_MODE_UNKNOWN,
+	USB4604_MODE_HUB,
+	USB4604_MODE_STANDBY,
+};
+
+struct usb4604 {
+	enum usb4604_mode	mode;
+	struct device		*dev;
+	struct gpio_desc	*gpio_reset;
+};
+
+static void usb4604_reset(struct usb4604 *hub, int state)
+{
+	gpiod_set_value_cansleep(hub->gpio_reset, state);
+
+	/* Wait for i2c logic to come up */
+	if (state)
+		msleep(250);
+}
+
+static int usb4604_connect(struct usb4604 *hub)
+{
+	struct device *dev = hub->dev;
+	struct i2c_client *client = to_i2c_client(dev);
+	int err;
+	u8 connect_cmd[] = { 0xaa, 0x55, 0x00 };
+
+	usb4604_reset(hub, 1);
+
+	err = i2c_master_send(client, connect_cmd, ARRAY_SIZE(connect_cmd));
+	if (err < 0) {
+		usb4604_reset(hub, 0);
+		return err;
+	}
+
+	hub->mode = USB4604_MODE_HUB;
+	dev_dbg(dev, "switched to HUB mode\n");
+
+	return 0;
+}
+
+static int usb4604_switch_mode(struct usb4604 *hub, enum usb4604_mode mode)
+{
+	struct device *dev = hub->dev;
+	int err = 0;
+
+	switch (mode) {
+	case USB4604_MODE_HUB:
+		err = usb4604_connect(hub);
+		break;
+
+	case USB4604_MODE_STANDBY:
+		usb4604_reset(hub, 0);
+		dev_dbg(dev, "switched to STANDBY mode\n");
+		break;
+
+	default:
+		dev_err(dev, "unknown mode is requested\n");
+		err = -EINVAL;
+		break;
+	}
+
+	return err;
+}
+
+static int usb4604_probe(struct usb4604 *hub)
+{
+	struct device *dev = hub->dev;
+	struct device_node *np = dev->of_node;
+	struct gpio_desc *gpio;
+	u32 mode = USB4604_MODE_HUB;
+
+	gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_LOW);
+	if (IS_ERR(gpio))
+		return PTR_ERR(gpio);
+	hub->gpio_reset = gpio;
+
+	if (of_property_read_u32(np, "initial-mode", &hub->mode))
+		hub->mode = mode;
+
+	return usb4604_switch_mode(hub, hub->mode);
+}
+
+static int usb4604_i2c_probe(struct i2c_client *i2c)
+{
+	struct usb4604 *hub;
+
+	hub = devm_kzalloc(&i2c->dev, sizeof(*hub), GFP_KERNEL);
+	if (!hub)
+		return -ENOMEM;
+
+	i2c_set_clientdata(i2c, hub);
+	hub->dev = &i2c->dev;
+
+	return usb4604_probe(hub);
+}
+
+static int __maybe_unused usb4604_i2c_suspend(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct usb4604 *hub = i2c_get_clientdata(client);
+
+	usb4604_switch_mode(hub, USB4604_MODE_STANDBY);
+
+	return 0;
+}
+
+static int __maybe_unused usb4604_i2c_resume(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct usb4604 *hub = i2c_get_clientdata(client);
+
+	usb4604_switch_mode(hub, hub->mode);
+
+	return 0;
+}
+
+static SIMPLE_DEV_PM_OPS(usb4604_i2c_pm_ops, usb4604_i2c_suspend,
+		usb4604_i2c_resume);
+
+static const struct i2c_device_id usb4604_id[] = {
+	{ .name = "usb4604" },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, usb4604_id);
+
+#ifdef CONFIG_OF
+static const struct of_device_id usb4604_of_match[] = {
+	{ .compatible = "smsc,usb4604" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, usb4604_of_match);
+#endif
+
+static struct i2c_driver usb4604_i2c_driver = {
+	.driver = {
+		.name = "usb4604",
+		.pm = pm_ptr(&usb4604_i2c_pm_ops),
+		.of_match_table = of_match_ptr(usb4604_of_match),
+	},
+	.probe		= usb4604_i2c_probe,
+	.id_table	= usb4604_id,
+};
+module_i2c_driver(usb4604_i2c_driver);
+
+MODULE_DESCRIPTION("USB4604 USB HUB driver");
+MODULE_LICENSE("GPL v2");