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, 115 insertions, 0 deletions

diff --git a/drivers/acpi/fan.h b/drivers/acpi/fan.h
new file mode 100644
index 000000000..e20d6ad9d
--- /dev/null
+++ b/drivers/acpi/fan.h
@@ -0,0 +1,115 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+/*
+ * ACPI fan device IDs are shared between the fan driver and the device power
+ * management code.
+ *
+ * Add new device IDs before the generic ACPI fan one.
+ */
+
+#ifndef _ACPI_FAN_H_
+#define _ACPI_FAN_H_
+
+#include <linux/device.h>
+#include <linux/limits.h>
+#include <linux/types.h>
+
+#define ACPI_FAN_DEVICE_IDS						\
+	{ .id = "INT3404" },	/* Fan */				\
+	{ .id = "INTC1044" },	/* Fan for Tiger Lake generation */	\
+	{ .id = "INTC1048" },	/* Fan for Alder Lake generation */	\
+	{ .id = "INTC1063" },	/* Fan for Meteor Lake generation */	\
+	{ .id = "INTC106A" },	/* Fan for Lunar Lake generation */	\
+	{ .id = "INTC10A2" },	/* Fan for Raptor Lake generation */	\
+	{ .id = "INTC10D6" },	/* Fan for Panther Lake generation */	\
+	{ .id = "INTC10FE" },	/* Fan for Wildcat Lake generation */	\
+	{ .id = "INTC10F5" },	/* Fan for Nova Lake generation */	\
+	{ .id = "PNP0C0B" }	/* Generic ACPI fan */
+
+#define ACPI_FPS_NAME_LEN	20
+
+struct acpi_fan_fps {
+	u64 control;
+	u64 trip_point;
+	u64 speed;
+	u64 noise_level;
+	u64 power;
+	char name[ACPI_FPS_NAME_LEN];
+	struct device_attribute dev_attr;
+};
+
+struct acpi_fan_fif {
+	u8 revision;
+	u8 fine_grain_ctrl;
+	u8 step_size;
+	u8 low_speed_notification;
+};
+
+struct acpi_fan_fst {
+	u64 revision;
+	u64 control;
+	u64 speed;
+};
+
+struct acpi_fan {
+	acpi_handle handle;
+	bool acpi4;
+	bool has_fst;
+	struct acpi_fan_fif fif;
+	struct acpi_fan_fps *fps;
+	int fps_count;
+	/* A value of 0 means that trippoint-related functions are not supported */
+	u32 fan_trip_granularity;
+#if IS_REACHABLE(CONFIG_HWMON)
+	struct device *hdev;
+#endif
+	struct thermal_cooling_device *cdev;
+	struct device_attribute fst_speed;
+	struct device_attribute fine_grain_control;
+};
+
+/**
+ * acpi_fan_speed_valid - Check if fan speed value is valid
+ * @speed: Speed value returned by the ACPI firmware
+ *
+ * Check if the fan speed value returned by the ACPI firmware is valid. This function is
+ * necessary as ACPI firmware implementations can return 0xFFFFFFFF to signal that the
+ * ACPI fan does not support speed reporting. Additionally, some buggy ACPI firmware
+ * implementations return a value larger than the 32-bit integer value defined by
+ * the ACPI specification when using placeholder values. Such invalid values are also
+ * detected by this function.
+ *
+ * Returns: True if the fan speed value is valid, false otherwise.
+ */
+static inline bool acpi_fan_speed_valid(u64 speed)
+{
+	return speed < U32_MAX;
+}
+
+/**
+ * acpi_fan_power_valid - Check if fan power value is valid
+ * @power: Power value returned by the ACPI firmware
+ *
+ * Check if the fan power value returned by the ACPI firmware is valid.
+ * See acpi_fan_speed_valid() for details.
+ *
+ * Returns: True if the fan power value is valid, false otherwise.
+ */
+static inline bool acpi_fan_power_valid(u64 power)
+{
+	return power < U32_MAX;
+}
+
+int acpi_fan_get_fst(acpi_handle handle, struct acpi_fan_fst *fst);
+int acpi_fan_create_attributes(struct acpi_device *device);
+void acpi_fan_delete_attributes(struct acpi_device *device);
+
+#if IS_REACHABLE(CONFIG_HWMON)
+int devm_acpi_fan_create_hwmon(struct device *dev);
+void acpi_fan_notify_hwmon(struct device *dev);
+#else
+static inline int devm_acpi_fan_create_hwmon(struct device *dev) { return 0; };
+static inline void acpi_fan_notify_hwmon(struct device *dev) { };
+#endif
+
+#endif