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, 148 insertions, 0 deletions

diff --git a/drivers/input/misc/wm831x-on.c b/drivers/input/misc/wm831x-on.c
new file mode 100644
index 000000000..18eb319bc
--- /dev/null
+++ b/drivers/input/misc/wm831x-on.c
@@ -0,0 +1,148 @@
+/*
+ * wm831x-on.c - WM831X ON pin driver
+ *
+ * Copyright (C) 2009 Wolfson Microelectronics plc
+ *
+ * This file is subject to the terms and conditions of the GNU General
+ * Public License. See the file "COPYING" in the main directory of this
+ * archive for more details.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/input.h>
+#include <linux/interrupt.h>
+#include <linux/platform_device.h>
+#include <linux/workqueue.h>
+#include <linux/mfd/wm831x/core.h>
+
+struct wm831x_on {
+	struct input_dev *dev;
+	struct delayed_work work;
+	struct wm831x *wm831x;
+};
+
+/*
+ * The chip gives us an interrupt when the ON pin is asserted but we
+ * then need to poll to see when the pin is deasserted.
+ */
+static void wm831x_poll_on(struct work_struct *work)
+{
+	struct wm831x_on *wm831x_on = container_of(work, struct wm831x_on,
+						   work.work);
+	struct wm831x *wm831x = wm831x_on->wm831x;
+	int poll, ret;
+
+	ret = wm831x_reg_read(wm831x, WM831X_ON_PIN_CONTROL);
+	if (ret >= 0) {
+		poll = !(ret & WM831X_ON_PIN_STS);
+
+		input_report_key(wm831x_on->dev, KEY_POWER, poll);
+		input_sync(wm831x_on->dev);
+	} else {
+		dev_err(wm831x->dev, "Failed to read ON status: %d\n", ret);
+		poll = 1;
+	}
+
+	if (poll)
+		schedule_delayed_work(&wm831x_on->work, 100);
+}
+
+static irqreturn_t wm831x_on_irq(int irq, void *data)
+{
+	struct wm831x_on *wm831x_on = data;
+
+	schedule_delayed_work(&wm831x_on->work, 0);
+
+	return IRQ_HANDLED;
+}
+
+static int wm831x_on_probe(struct platform_device *pdev)
+{
+	struct wm831x *wm831x = dev_get_drvdata(pdev->dev.parent);
+	struct wm831x_on *wm831x_on;
+	int irq = wm831x_irq(wm831x, platform_get_irq(pdev, 0));
+	int ret;
+
+	wm831x_on = devm_kzalloc(&pdev->dev, sizeof(struct wm831x_on),
+				 GFP_KERNEL);
+	if (!wm831x_on) {
+		dev_err(&pdev->dev, "Can't allocate data\n");
+		return -ENOMEM;
+	}
+
+	wm831x_on->wm831x = wm831x;
+	INIT_DELAYED_WORK(&wm831x_on->work, wm831x_poll_on);
+
+	wm831x_on->dev = devm_input_allocate_device(&pdev->dev);
+	if (!wm831x_on->dev) {
+		dev_err(&pdev->dev, "Can't allocate input dev\n");
+		ret = -ENOMEM;
+		goto err;
+	}
+
+	wm831x_on->dev->evbit[0] = BIT_MASK(EV_KEY);
+	wm831x_on->dev->keybit[BIT_WORD(KEY_POWER)] = BIT_MASK(KEY_POWER);
+	wm831x_on->dev->name = "wm831x_on";
+	wm831x_on->dev->phys = "wm831x_on/input0";
+	wm831x_on->dev->dev.parent = &pdev->dev;
+
+	ret = request_threaded_irq(irq, NULL, wm831x_on_irq,
+				   IRQF_TRIGGER_RISING | IRQF_ONESHOT,
+				   "wm831x_on",
+				   wm831x_on);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "Unable to request IRQ: %d\n", ret);
+		goto err_input_dev;
+	}
+	ret = input_register_device(wm831x_on->dev);
+	if (ret) {
+		dev_dbg(&pdev->dev, "Can't register input device: %d\n", ret);
+		goto err_irq;
+	}
+
+	platform_set_drvdata(pdev, wm831x_on);
+
+	return 0;
+
+err_irq:
+	free_irq(irq, wm831x_on);
+err_input_dev:
+err:
+	return ret;
+}
+
+static void wm831x_on_remove(struct platform_device *pdev)
+{
+	struct wm831x_on *wm831x_on = platform_get_drvdata(pdev);
+	int irq = platform_get_irq(pdev, 0);
+
+	free_irq(irq, wm831x_on);
+	cancel_delayed_work_sync(&wm831x_on->work);
+}
+
+static struct platform_driver wm831x_on_driver = {
+	.probe		= wm831x_on_probe,
+	.remove		= wm831x_on_remove,
+	.driver		= {
+		.name	= "wm831x-on",
+	},
+};
+module_platform_driver(wm831x_on_driver);
+
+MODULE_ALIAS("platform:wm831x-on");
+MODULE_DESCRIPTION("WM831x ON pin");
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Mark Brown <broonie@opensource.wolfsonmicro.com>");
+