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, 238 insertions, 0 deletions

diff --git a/drivers/input/keyboard/cypress-sf.c b/drivers/input/keyboard/cypress-sf.c
new file mode 100644
index 000000000..4b2ae07f3
--- /dev/null
+++ b/drivers/input/keyboard/cypress-sf.c
@@ -0,0 +1,238 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Cypress StreetFighter Touchkey Driver
+ *
+ * Copyright (c) 2021 Yassine Oudjana <y.oudjana@protonmail.com>
+ */
+
+#include <linux/bitmap.h>
+#include <linux/bitops.h>
+#include <linux/device.h>
+#include <linux/i2c.h>
+#include <linux/input.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/pm.h>
+#include <linux/regulator/consumer.h>
+
+#define CYPRESS_SF_DEV_NAME "cypress-sf"
+
+#define CYPRESS_SF_REG_BUTTON_STATUS	0x4a
+
+struct cypress_sf_data {
+	struct i2c_client *client;
+	struct input_dev *input_dev;
+	struct regulator_bulk_data regulators[2];
+	u32 *keycodes;
+	unsigned long keystates;
+	int num_keys;
+};
+
+static irqreturn_t cypress_sf_irq_handler(int irq, void *devid)
+{
+	struct cypress_sf_data *touchkey = devid;
+	unsigned long keystates, changed;
+	bool new_state;
+	int val, key;
+
+	val = i2c_smbus_read_byte_data(touchkey->client,
+				       CYPRESS_SF_REG_BUTTON_STATUS);
+	if (val < 0) {
+		dev_err(&touchkey->client->dev,
+			"Failed to read button status: %d", val);
+		return IRQ_NONE;
+	}
+	keystates = val;
+
+	bitmap_xor(&changed, &keystates, &touchkey->keystates,
+		   touchkey->num_keys);
+
+	for_each_set_bit(key, &changed, touchkey->num_keys) {
+		new_state = keystates & BIT(key);
+		dev_dbg(&touchkey->client->dev,
+			"Key %d changed to %d", key, new_state);
+		input_report_key(touchkey->input_dev,
+				 touchkey->keycodes[key], new_state);
+	}
+
+	input_sync(touchkey->input_dev);
+	touchkey->keystates = keystates;
+
+	return IRQ_HANDLED;
+}
+
+static void cypress_sf_disable_regulators(void *arg)
+{
+	struct cypress_sf_data *touchkey = arg;
+
+	regulator_bulk_disable(ARRAY_SIZE(touchkey->regulators),
+			       touchkey->regulators);
+}
+
+static int cypress_sf_probe(struct i2c_client *client)
+{
+	struct cypress_sf_data *touchkey;
+	int key, error;
+
+	touchkey = devm_kzalloc(&client->dev, sizeof(*touchkey), GFP_KERNEL);
+	if (!touchkey)
+		return -ENOMEM;
+
+	touchkey->client = client;
+	i2c_set_clientdata(client, touchkey);
+
+	touchkey->regulators[0].supply = "vdd";
+	touchkey->regulators[1].supply = "avdd";
+
+	error = devm_regulator_bulk_get(&client->dev,
+					ARRAY_SIZE(touchkey->regulators),
+					touchkey->regulators);
+	if (error) {
+		dev_err(&client->dev, "Failed to get regulators: %d\n", error);
+		return error;
+	}
+
+	touchkey->num_keys = device_property_read_u32_array(&client->dev,
+							    "linux,keycodes",
+							    NULL, 0);
+	if (touchkey->num_keys < 0) {
+		/* Default key count */
+		touchkey->num_keys = 2;
+	}
+
+	touchkey->keycodes = devm_kcalloc(&client->dev,
+					  touchkey->num_keys,
+					  sizeof(*touchkey->keycodes),
+					  GFP_KERNEL);
+	if (!touchkey->keycodes)
+		return -ENOMEM;
+
+	error = device_property_read_u32_array(&client->dev, "linux,keycodes",
+					       touchkey->keycodes,
+					       touchkey->num_keys);
+
+	if (error) {
+		dev_warn(&client->dev,
+			 "Failed to read keycodes: %d, using defaults\n",
+			 error);
+
+		/* Default keycodes */
+		touchkey->keycodes[0] = KEY_BACK;
+		touchkey->keycodes[1] = KEY_MENU;
+	}
+
+	error = regulator_bulk_enable(ARRAY_SIZE(touchkey->regulators),
+				      touchkey->regulators);
+	if (error) {
+		dev_err(&client->dev,
+			"Failed to enable regulators: %d\n", error);
+		return error;
+	}
+
+	error = devm_add_action_or_reset(&client->dev,
+					 cypress_sf_disable_regulators,
+					 touchkey);
+	if (error)
+		return error;
+
+	touchkey->input_dev = devm_input_allocate_device(&client->dev);
+	if (!touchkey->input_dev) {
+		dev_err(&client->dev, "Failed to allocate input device\n");
+		return -ENOMEM;
+	}
+
+	touchkey->input_dev->name = CYPRESS_SF_DEV_NAME;
+	touchkey->input_dev->id.bustype = BUS_I2C;
+
+	for (key = 0; key < touchkey->num_keys; ++key)
+		input_set_capability(touchkey->input_dev,
+				     EV_KEY, touchkey->keycodes[key]);
+
+	error = input_register_device(touchkey->input_dev);
+	if (error) {
+		dev_err(&client->dev,
+			"Failed to register input device: %d\n", error);
+		return error;
+	}
+
+	error = devm_request_threaded_irq(&client->dev, client->irq,
+					  NULL, cypress_sf_irq_handler,
+					  IRQF_ONESHOT,
+					  CYPRESS_SF_DEV_NAME, touchkey);
+	if (error) {
+		dev_err(&client->dev,
+			"Failed to register threaded irq: %d", error);
+		return error;
+	}
+
+	return 0;
+};
+
+static int cypress_sf_suspend(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct cypress_sf_data *touchkey = i2c_get_clientdata(client);
+	int error;
+
+	disable_irq(client->irq);
+
+	error = regulator_bulk_disable(ARRAY_SIZE(touchkey->regulators),
+				       touchkey->regulators);
+	if (error) {
+		dev_err(dev, "Failed to disable regulators: %d", error);
+		enable_irq(client->irq);
+		return error;
+	}
+
+	return 0;
+}
+
+static int cypress_sf_resume(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct cypress_sf_data *touchkey = i2c_get_clientdata(client);
+	int error;
+
+	error = regulator_bulk_enable(ARRAY_SIZE(touchkey->regulators),
+				      touchkey->regulators);
+	if (error) {
+		dev_err(dev, "Failed to enable regulators: %d", error);
+		return error;
+	}
+
+	enable_irq(client->irq);
+
+	return 0;
+}
+
+static DEFINE_SIMPLE_DEV_PM_OPS(cypress_sf_pm_ops,
+				cypress_sf_suspend, cypress_sf_resume);
+
+static const struct i2c_device_id cypress_sf_id_table[] = {
+	{ .name = CYPRESS_SF_DEV_NAME },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, cypress_sf_id_table);
+
+#ifdef CONFIG_OF
+static const struct of_device_id cypress_sf_of_match[] = {
+	{ .compatible = "cypress,sf3155", },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, cypress_sf_of_match);
+#endif
+
+static struct i2c_driver cypress_sf_driver = {
+	.driver = {
+		.name = CYPRESS_SF_DEV_NAME,
+		.pm = pm_sleep_ptr(&cypress_sf_pm_ops),
+		.of_match_table = of_match_ptr(cypress_sf_of_match),
+	},
+	.id_table = cypress_sf_id_table,
+	.probe = cypress_sf_probe,
+};
+module_i2c_driver(cypress_sf_driver);
+
+MODULE_AUTHOR("Yassine Oudjana <y.oudjana@protonmail.com>");
+MODULE_DESCRIPTION("Cypress StreetFighter Touchkey Driver");
+MODULE_LICENSE("GPL v2");