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, 246 insertions, 0 deletions

diff --git a/drivers/mfd/lp8788.c b/drivers/mfd/lp8788.c
new file mode 100644
index 000000000..32f255378
--- /dev/null
+++ b/drivers/mfd/lp8788.c
@@ -0,0 +1,246 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * TI LP8788 MFD - core interface
+ *
+ * Copyright 2012 Texas Instruments
+ *
+ * Author: Milo(Woogyom) Kim <milo.kim@ti.com>
+ */
+
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/mfd/core.h>
+#include <linux/mfd/lp8788.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+
+#define MAX_LP8788_REGISTERS		0xA2
+
+#define MFD_DEV_SIMPLE(_name)					\
+{								\
+	.name = LP8788_DEV_##_name,				\
+}
+
+#define MFD_DEV_WITH_ID(_name, _id)				\
+{								\
+	.name = LP8788_DEV_##_name,				\
+	.id = _id,						\
+}
+
+#define MFD_DEV_WITH_RESOURCE(_name, _resource, num_resource)	\
+{								\
+	.name = LP8788_DEV_##_name,				\
+	.resources = _resource,					\
+	.num_resources = num_resource,				\
+}
+
+static const struct resource chg_irqs[] = {
+	/* Charger Interrupts */
+	{
+		.start = LP8788_INT_CHG_INPUT_STATE,
+		.end   = LP8788_INT_PRECHG_TIMEOUT,
+		.name  = LP8788_CHG_IRQ,
+		.flags = IORESOURCE_IRQ,
+	},
+	/* Power Routing Switch Interrupts */
+	{
+		.start = LP8788_INT_ENTER_SYS_SUPPORT,
+		.end   = LP8788_INT_EXIT_SYS_SUPPORT,
+		.name  = LP8788_PRSW_IRQ,
+		.flags = IORESOURCE_IRQ,
+	},
+	/* Battery Interrupts */
+	{
+		.start = LP8788_INT_BATT_LOW,
+		.end   = LP8788_INT_NO_BATT,
+		.name  = LP8788_BATT_IRQ,
+		.flags = IORESOURCE_IRQ,
+	},
+};
+
+static const struct resource rtc_irqs[] = {
+	{
+		.start = LP8788_INT_RTC_ALARM1,
+		.end   = LP8788_INT_RTC_ALARM2,
+		.name  = LP8788_ALM_IRQ,
+		.flags = IORESOURCE_IRQ,
+	},
+};
+
+static const struct mfd_cell lp8788_devs[] = {
+	/* 4 bucks */
+	MFD_DEV_WITH_ID(BUCK, 1),
+	MFD_DEV_WITH_ID(BUCK, 2),
+	MFD_DEV_WITH_ID(BUCK, 3),
+	MFD_DEV_WITH_ID(BUCK, 4),
+
+	/* 12 digital ldos */
+	MFD_DEV_WITH_ID(DLDO, 1),
+	MFD_DEV_WITH_ID(DLDO, 2),
+	MFD_DEV_WITH_ID(DLDO, 3),
+	MFD_DEV_WITH_ID(DLDO, 4),
+	MFD_DEV_WITH_ID(DLDO, 5),
+	MFD_DEV_WITH_ID(DLDO, 6),
+	MFD_DEV_WITH_ID(DLDO, 7),
+	MFD_DEV_WITH_ID(DLDO, 8),
+	MFD_DEV_WITH_ID(DLDO, 9),
+	MFD_DEV_WITH_ID(DLDO, 10),
+	MFD_DEV_WITH_ID(DLDO, 11),
+	MFD_DEV_WITH_ID(DLDO, 12),
+
+	/* 10 analog ldos */
+	MFD_DEV_WITH_ID(ALDO, 1),
+	MFD_DEV_WITH_ID(ALDO, 2),
+	MFD_DEV_WITH_ID(ALDO, 3),
+	MFD_DEV_WITH_ID(ALDO, 4),
+	MFD_DEV_WITH_ID(ALDO, 5),
+	MFD_DEV_WITH_ID(ALDO, 6),
+	MFD_DEV_WITH_ID(ALDO, 7),
+	MFD_DEV_WITH_ID(ALDO, 8),
+	MFD_DEV_WITH_ID(ALDO, 9),
+	MFD_DEV_WITH_ID(ALDO, 10),
+
+	/* ADC */
+	MFD_DEV_SIMPLE(ADC),
+
+	/* battery charger */
+	MFD_DEV_WITH_RESOURCE(CHARGER, chg_irqs, ARRAY_SIZE(chg_irqs)),
+
+	/* rtc */
+	MFD_DEV_WITH_RESOURCE(RTC, rtc_irqs, ARRAY_SIZE(rtc_irqs)),
+
+	/* backlight */
+	MFD_DEV_SIMPLE(BACKLIGHT),
+
+	/* current sink for vibrator */
+	MFD_DEV_SIMPLE(VIBRATOR),
+
+	/* current sink for keypad LED */
+	MFD_DEV_SIMPLE(KEYLED),
+};
+
+int lp8788_read_byte(struct lp8788 *lp, u8 reg, u8 *data)
+{
+	int ret;
+	unsigned int val;
+
+	ret = regmap_read(lp->regmap, reg, &val);
+	if (ret < 0) {
+		dev_err(lp->dev, "failed to read 0x%.2x\n", reg);
+		return ret;
+	}
+
+	*data = (u8)val;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(lp8788_read_byte);
+
+int lp8788_read_multi_bytes(struct lp8788 *lp, u8 reg, u8 *data, size_t count)
+{
+	return regmap_bulk_read(lp->regmap, reg, data, count);
+}
+EXPORT_SYMBOL_GPL(lp8788_read_multi_bytes);
+
+int lp8788_write_byte(struct lp8788 *lp, u8 reg, u8 data)
+{
+	return regmap_write(lp->regmap, reg, data);
+}
+EXPORT_SYMBOL_GPL(lp8788_write_byte);
+
+int lp8788_update_bits(struct lp8788 *lp, u8 reg, u8 mask, u8 data)
+{
+	return regmap_update_bits(lp->regmap, reg, mask, data);
+}
+EXPORT_SYMBOL_GPL(lp8788_update_bits);
+
+static int lp8788_platform_init(struct lp8788 *lp)
+{
+	struct lp8788_platform_data *pdata = lp->pdata;
+
+	return (pdata && pdata->init_func) ? pdata->init_func(lp) : 0;
+}
+
+static const struct regmap_config lp8788_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.max_register = MAX_LP8788_REGISTERS,
+};
+
+static int lp8788_probe(struct i2c_client *cl)
+{
+	struct lp8788 *lp;
+	struct lp8788_platform_data *pdata = dev_get_platdata(&cl->dev);
+	int ret;
+
+	lp = devm_kzalloc(&cl->dev, sizeof(struct lp8788), GFP_KERNEL);
+	if (!lp)
+		return -ENOMEM;
+
+	lp->regmap = devm_regmap_init_i2c(cl, &lp8788_regmap_config);
+	if (IS_ERR(lp->regmap)) {
+		ret = PTR_ERR(lp->regmap);
+		dev_err(&cl->dev, "regmap init i2c err: %d\n", ret);
+		return ret;
+	}
+
+	lp->pdata = pdata;
+	lp->dev = &cl->dev;
+	i2c_set_clientdata(cl, lp);
+
+	ret = lp8788_platform_init(lp);
+	if (ret)
+		return ret;
+
+	ret = lp8788_irq_init(lp, cl->irq);
+	if (ret)
+		return ret;
+
+	ret = mfd_add_devices(lp->dev, -1, lp8788_devs,
+			      ARRAY_SIZE(lp8788_devs), NULL, 0, NULL);
+	if (ret)
+		goto err_exit_irq;
+
+	return 0;
+
+err_exit_irq:
+	lp8788_irq_exit(lp);
+	return ret;
+}
+
+static void lp8788_remove(struct i2c_client *cl)
+{
+	struct lp8788 *lp = i2c_get_clientdata(cl);
+
+	mfd_remove_devices(lp->dev);
+	lp8788_irq_exit(lp);
+}
+
+static const struct i2c_device_id lp8788_ids[] = {
+	{ "lp8788" },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, lp8788_ids);
+
+static struct i2c_driver lp8788_driver = {
+	.driver = {
+		.name = "lp8788",
+	},
+	.probe = lp8788_probe,
+	.remove = lp8788_remove,
+	.id_table = lp8788_ids,
+};
+
+static int __init lp8788_init(void)
+{
+	return i2c_add_driver(&lp8788_driver);
+}
+subsys_initcall(lp8788_init);
+
+static void __exit lp8788_exit(void)
+{
+	i2c_del_driver(&lp8788_driver);
+}
+module_exit(lp8788_exit);
+
+MODULE_DESCRIPTION("TI LP8788 MFD Driver");
+MODULE_AUTHOR("Milo Kim");