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, 98 insertions, 0 deletions

diff --git a/drivers/mfd/da9055-i2c.c b/drivers/mfd/da9055-i2c.c
new file mode 100644
index 000000000..6c1981832
--- /dev/null
+++ b/drivers/mfd/da9055-i2c.c
@@ -0,0 +1,98 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+ /* I2C access for DA9055 PMICs.
+ *
+ * Copyright(c) 2012 Dialog Semiconductor Ltd.
+ *
+ * Author: David Dajun Chen <dchen@diasemi.com>
+ */
+
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/i2c.h>
+#include <linux/err.h>
+#include <linux/of.h>
+
+#include <linux/mfd/da9055/core.h>
+
+static int da9055_i2c_probe(struct i2c_client *i2c)
+{
+	struct da9055 *da9055;
+	int ret;
+
+	da9055 = devm_kzalloc(&i2c->dev, sizeof(struct da9055), GFP_KERNEL);
+	if (!da9055)
+		return -ENOMEM;
+
+	da9055->regmap = devm_regmap_init_i2c(i2c, &da9055_regmap_config);
+	if (IS_ERR(da9055->regmap)) {
+		ret = PTR_ERR(da9055->regmap);
+		dev_err(&i2c->dev, "Failed to allocate register map: %d\n",
+			ret);
+		return ret;
+	}
+
+	da9055->dev = &i2c->dev;
+	da9055->chip_irq = i2c->irq;
+
+	i2c_set_clientdata(i2c, da9055);
+
+	return da9055_device_init(da9055);
+}
+
+static void da9055_i2c_remove(struct i2c_client *i2c)
+{
+	struct da9055 *da9055 = i2c_get_clientdata(i2c);
+
+	da9055_device_exit(da9055);
+}
+
+/*
+ * DO NOT change the device Ids. The naming is intentionally specific as both
+ * the PMIC and CODEC parts of this chip are instantiated separately as I2C
+ * devices (both have configurable I2C addresses, and are to all intents and
+ * purposes separate). As a result there are specific DA9055 ids for PMIC
+ * and CODEC, which must be different to operate together.
+ */
+static const struct i2c_device_id da9055_i2c_id[] = {
+	{ "da9055-pmic" },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, da9055_i2c_id);
+
+static const struct of_device_id da9055_of_match[] = {
+	{ .compatible = "dlg,da9055-pmic", },
+	{ }
+};
+
+static struct i2c_driver da9055_i2c_driver = {
+	.probe = da9055_i2c_probe,
+	.remove = da9055_i2c_remove,
+	.id_table = da9055_i2c_id,
+	.driver = {
+		.name = "da9055-pmic",
+		.of_match_table = da9055_of_match,
+	},
+};
+
+static int __init da9055_i2c_init(void)
+{
+	int ret;
+
+	ret = i2c_add_driver(&da9055_i2c_driver);
+	if (ret != 0) {
+		pr_err("DA9055 I2C registration failed %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+subsys_initcall(da9055_i2c_init);
+
+static void __exit da9055_i2c_exit(void)
+{
+	i2c_del_driver(&da9055_i2c_driver);
+}
+module_exit(da9055_i2c_exit);
+
+MODULE_AUTHOR("David Dajun Chen <dchen@diasemi.com>");
+MODULE_DESCRIPTION("I2C driver for Dialog DA9055 PMIC");