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, 140 insertions, 0 deletions

diff --git a/drivers/extcon/extcon-max3355.c b/drivers/extcon/extcon-max3355.c
new file mode 100644
index 000000000..d687d178a
--- /dev/null
+++ b/drivers/extcon/extcon-max3355.c
@@ -0,0 +1,140 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Maxim Integrated MAX3355 USB OTG chip extcon driver
+ *
+ * Copyright (C)  2014-2015 Cogent Embedded, Inc.
+ * Author: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
+ */
+
+#include <linux/extcon-provider.h>
+#include <linux/gpio/consumer.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+
+struct max3355_data {
+	struct extcon_dev *edev;
+	struct gpio_desc *id_gpiod;
+	struct gpio_desc *shdn_gpiod;
+};
+
+static const unsigned int max3355_cable[] = {
+	EXTCON_USB,
+	EXTCON_USB_HOST,
+	EXTCON_NONE,
+};
+
+static irqreturn_t max3355_id_irq(int irq, void *dev_id)
+{
+	struct max3355_data *data = dev_id;
+	int id = gpiod_get_value_cansleep(data->id_gpiod);
+
+	if (id) {
+		/*
+		 * ID = 1 means USB HOST cable detached.
+		 * As we don't have event for USB peripheral cable attached,
+		 * we simulate USB peripheral attach here.
+		 */
+		extcon_set_state_sync(data->edev, EXTCON_USB_HOST, false);
+		extcon_set_state_sync(data->edev, EXTCON_USB, true);
+	} else {
+		/*
+		 * ID = 0 means USB HOST cable attached.
+		 * As we don't have event for USB peripheral cable detached,
+		 * we simulate USB peripheral detach here.
+		 */
+		extcon_set_state_sync(data->edev, EXTCON_USB, false);
+		extcon_set_state_sync(data->edev, EXTCON_USB_HOST, true);
+	}
+
+	return IRQ_HANDLED;
+}
+
+static int max3355_probe(struct platform_device *pdev)
+{
+	struct max3355_data *data;
+	struct gpio_desc *gpiod;
+	int irq, err;
+
+	data = devm_kzalloc(&pdev->dev, sizeof(struct max3355_data),
+			    GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	gpiod = devm_gpiod_get(&pdev->dev, "id", GPIOD_IN);
+	if (IS_ERR(gpiod)) {
+		dev_err(&pdev->dev, "failed to get ID_OUT GPIO\n");
+		return PTR_ERR(gpiod);
+	}
+	data->id_gpiod = gpiod;
+
+	gpiod = devm_gpiod_get(&pdev->dev, "maxim,shdn", GPIOD_OUT_HIGH);
+	if (IS_ERR(gpiod)) {
+		dev_err(&pdev->dev, "failed to get SHDN# GPIO\n");
+		return PTR_ERR(gpiod);
+	}
+	data->shdn_gpiod = gpiod;
+
+	data->edev = devm_extcon_dev_allocate(&pdev->dev, max3355_cable);
+	if (IS_ERR(data->edev)) {
+		dev_err(&pdev->dev, "failed to allocate extcon device\n");
+		return PTR_ERR(data->edev);
+	}
+
+	err = devm_extcon_dev_register(&pdev->dev, data->edev);
+	if (err < 0) {
+		dev_err(&pdev->dev, "failed to register extcon device\n");
+		return err;
+	}
+
+	irq = gpiod_to_irq(data->id_gpiod);
+	if (irq < 0) {
+		dev_err(&pdev->dev, "failed to translate ID_OUT GPIO to IRQ\n");
+		return irq;
+	}
+
+	err = devm_request_threaded_irq(&pdev->dev, irq, NULL, max3355_id_irq,
+					IRQF_ONESHOT | IRQF_NO_SUSPEND |
+					IRQF_TRIGGER_RISING |
+					IRQF_TRIGGER_FALLING,
+					pdev->name, data);
+	if (err < 0) {
+		dev_err(&pdev->dev, "failed to request ID_OUT IRQ\n");
+		return err;
+	}
+
+	platform_set_drvdata(pdev, data);
+
+	/* Perform initial detection */
+	max3355_id_irq(irq, data);
+
+	return 0;
+}
+
+static void max3355_remove(struct platform_device *pdev)
+{
+	struct max3355_data *data = platform_get_drvdata(pdev);
+
+	gpiod_set_value_cansleep(data->shdn_gpiod, 0);
+}
+
+static const struct of_device_id max3355_match_table[] = {
+	{ .compatible = "maxim,max3355", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, max3355_match_table);
+
+static struct platform_driver max3355_driver = {
+	.probe		= max3355_probe,
+	.remove		= max3355_remove,
+	.driver		= {
+		.name	= "extcon-max3355",
+		.of_match_table = max3355_match_table,
+	},
+};
+
+module_platform_driver(max3355_driver);
+
+MODULE_AUTHOR("Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>");
+MODULE_DESCRIPTION("Maxim MAX3355 extcon driver");
+MODULE_LICENSE("GPL v2");