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, 130 insertions, 0 deletions

diff --git a/drivers/input/misc/ab8500-ponkey.c b/drivers/input/misc/ab8500-ponkey.c
new file mode 100644
index 000000000..a9b901368
--- /dev/null
+++ b/drivers/input/misc/ab8500-ponkey.c
@@ -0,0 +1,130 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) ST-Ericsson SA 2010
+ *
+ * Author: Sundar Iyer <sundar.iyer@stericsson.com> for ST-Ericsson
+ *
+ * AB8500 Power-On Key handler
+ */
+
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/input.h>
+#include <linux/interrupt.h>
+#include <linux/mfd/abx500/ab8500.h>
+#include <linux/of.h>
+#include <linux/slab.h>
+
+/**
+ * struct ab8500_ponkey - ab8500 ponkey information
+ * @idev: pointer to input device
+ * @ab8500: ab8500 parent
+ * @irq_dbf: irq number for falling transition
+ * @irq_dbr: irq number for rising transition
+ */
+struct ab8500_ponkey {
+	struct input_dev	*idev;
+	struct ab8500		*ab8500;
+	int			irq_dbf;
+	int			irq_dbr;
+};
+
+/* AB8500 gives us an interrupt when ONKEY is held */
+static irqreturn_t ab8500_ponkey_handler(int irq, void *data)
+{
+	struct ab8500_ponkey *ponkey = data;
+
+	if (irq == ponkey->irq_dbf)
+		input_report_key(ponkey->idev, KEY_POWER, true);
+	else if (irq == ponkey->irq_dbr)
+		input_report_key(ponkey->idev, KEY_POWER, false);
+
+	input_sync(ponkey->idev);
+
+	return IRQ_HANDLED;
+}
+
+static int ab8500_ponkey_probe(struct platform_device *pdev)
+{
+	struct ab8500 *ab8500 = dev_get_drvdata(pdev->dev.parent);
+	struct ab8500_ponkey *ponkey;
+	struct input_dev *input;
+	int irq_dbf, irq_dbr;
+	int error;
+
+	irq_dbf = platform_get_irq_byname(pdev, "ONKEY_DBF");
+	if (irq_dbf < 0)
+		return irq_dbf;
+
+	irq_dbr = platform_get_irq_byname(pdev, "ONKEY_DBR");
+	if (irq_dbr < 0)
+		return irq_dbr;
+
+	ponkey = devm_kzalloc(&pdev->dev, sizeof(struct ab8500_ponkey),
+			      GFP_KERNEL);
+	if (!ponkey)
+		return -ENOMEM;
+
+	input = devm_input_allocate_device(&pdev->dev);
+	if (!input)
+		return -ENOMEM;
+
+	ponkey->idev = input;
+	ponkey->ab8500 = ab8500;
+	ponkey->irq_dbf = irq_dbf;
+	ponkey->irq_dbr = irq_dbr;
+
+	input->name = "AB8500 POn(PowerOn) Key";
+	input->dev.parent = &pdev->dev;
+
+	input_set_capability(input, EV_KEY, KEY_POWER);
+
+	error = devm_request_any_context_irq(&pdev->dev, ponkey->irq_dbf,
+					     ab8500_ponkey_handler, 0,
+					     "ab8500-ponkey-dbf", ponkey);
+	if (error < 0) {
+		dev_err(ab8500->dev, "Failed to request dbf IRQ#%d: %d\n",
+			ponkey->irq_dbf, error);
+		return error;
+	}
+
+	error = devm_request_any_context_irq(&pdev->dev, ponkey->irq_dbr,
+					     ab8500_ponkey_handler, 0,
+					     "ab8500-ponkey-dbr", ponkey);
+	if (error < 0) {
+		dev_err(ab8500->dev, "Failed to request dbr IRQ#%d: %d\n",
+			ponkey->irq_dbr, error);
+		return error;
+	}
+
+	error = input_register_device(ponkey->idev);
+	if (error) {
+		dev_err(ab8500->dev, "Can't register input device: %d\n", error);
+		return error;
+	}
+
+	return 0;
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id ab8500_ponkey_match[] = {
+	{ .compatible = "stericsson,ab8500-ponkey", },
+	{}
+};
+MODULE_DEVICE_TABLE(of, ab8500_ponkey_match);
+#endif
+
+static struct platform_driver ab8500_ponkey_driver = {
+	.driver		= {
+		.name	= "ab8500-poweron-key",
+		.of_match_table = of_match_ptr(ab8500_ponkey_match),
+	},
+	.probe		= ab8500_ponkey_probe,
+};
+module_platform_driver(ab8500_ponkey_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Sundar Iyer <sundar.iyer@stericsson.com>");
+MODULE_DESCRIPTION("ST-Ericsson AB8500 Power-ON(Pon) Key driver");