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, 259 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-class-thermal b/Documentation/ABI/testing/sysfs-class-thermal
new file mode 100644
index 000000000..968d89e15
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class-thermal
@@ -0,0 +1,259 @@
+What:		/sys/class/thermal/thermal_zoneX/type
+Description:
+		Strings which represent the thermal zone type.
+		This is given by thermal zone driver as part of registration.
+		E.g: "acpitz" indicates it's an ACPI thermal device.
+		In order to keep it consistent with hwmon sys attribute; this
+		should be a short, lowercase string, not containing spaces nor
+		dashes.
+
+		RO, Required
+
+What:		/sys/class/thermal/thermal_zoneX/temp
+Description:
+		Current temperature as reported by thermal zone (sensor).
+
+		Unit: millidegree Celsius
+
+		RO, Required
+
+What:		/sys/class/thermal/thermal_zoneX/mode
+Description:
+		One of the predefined values in [enabled, disabled].
+		This file gives information about the algorithm that is
+		currently managing the thermal zone. It can be either default
+		kernel based algorithm or user space application.
+
+		enabled
+				enable Kernel Thermal management.
+		disabled
+				Preventing kernel thermal zone driver actions upon
+				trip points so that user application can take full
+				charge of the thermal management.
+
+		RW, Optional
+
+What:		/sys/class/thermal/thermal_zoneX/policy
+Description:
+		One of the various thermal governors used for a particular zone.
+
+		RW, Required
+
+What:		/sys/class/thermal/thermal_zoneX/available_policies
+Description:
+		Available thermal governors which can be used for a
+		particular zone.
+
+		RO, Required
+
+What:		/sys/class/thermal/thermal_zoneX/trip_point_Y_temp
+Description:
+		The temperature above which trip point will be fired.
+
+		Unit: millidegree Celsius
+
+		RO, Optional
+
+What:		/sys/class/thermal/thermal_zoneX/trip_point_Y_type
+Description:
+		Strings which indicate the type of the trip point.
+
+		E.g. it can be one of critical, hot, passive, `active[0-*]`
+		for ACPI thermal zone.
+
+		RO, Optional
+
+What:		/sys/class/thermal/thermal_zoneX/trip_point_Y_hyst
+Description:
+		The hysteresis value for a trip point, represented as an
+		integer.
+
+		Unit: Celsius
+
+		RW, Optional
+
+What:		/sys/class/thermal/thermal_zoneX/cdevY
+Description:
+	Sysfs link to the thermal cooling device node where the sys I/F
+	for cooling device throttling control represents.
+
+	RO, Optional
+
+What:		/sys/class/thermal/thermal_zoneX/cdevY_trip_point
+Description:
+		The trip point in this thermal zone which `cdev[0-*]` is
+		associated with; -1 means the cooling device is not
+		associated with any trip point.
+
+		RO, Optional
+
+What:		/sys/class/thermal/thermal_zoneX/cdevY_weight
+Description:
+		The influence of `cdev[0-*]` in this thermal zone. This value
+		is relative to the rest of cooling devices in the thermal
+		zone. For example, if a cooling device has a weight double
+		than that of other, it's twice as effective in cooling the
+		thermal zone.
+
+		RW, Optional
+
+What:		/sys/class/thermal/thermal_zoneX/emul_temp
+Description:
+		Interface to set the emulated temperature method in thermal zone
+		(sensor). After setting this temperature, the thermal zone may
+		pass this temperature to platform emulation function if
+		registered or cache it locally. This is useful in debugging
+		different temperature threshold and its associated cooling
+		action. This is write only node and writing 0 on this node
+		should disable emulation.
+
+		Unit: millidegree Celsius
+
+		WO, Optional
+
+		WARNING:
+		    Be careful while enabling this option on production systems,
+		    because userland can easily disable the thermal policy by simply
+		    flooding this sysfs node with low temperature values.
+
+
+What:		/sys/class/thermal/thermal_zoneX/k_d
+Description:
+		The derivative term of the power allocator governor's PID
+		controller. For more information see
+		Documentation/driver-api/thermal/power_allocator.rst
+
+		RW, Optional
+
+What:		/sys/class/thermal/thermal_zoneX/k_i
+Description:
+		The integral term of the power allocator governor's PID
+		controller. This term allows the PID controller to compensate
+		for long term drift. For more information see
+		Documentation/driver-api/thermal/power_allocator.rst
+
+		RW, Optional
+
+What:		/sys/class/thermal/thermal_zoneX/k_po
+Description:
+		The proportional term of the power allocator governor's PID
+		controller during temperature overshoot. Temperature overshoot
+		is when the current temperature is above the "desired
+		temperature" trip point. For more information see
+		Documentation/driver-api/thermal/power_allocator.rst
+
+		RW, Optional
+
+What:		/sys/class/thermal/thermal_zoneX/k_pu
+Description:
+		The proportional term of the power allocator governor's PID
+		controller during temperature undershoot. Temperature undershoot
+		is when the current temperature is below the "desired
+		temperature" trip point. For more information see
+		Documentation/driver-api/thermal/power_allocator.rst
+
+		RW, Optional
+
+What:		/sys/class/thermal/thermal_zoneX/integral_cutoff
+Description:
+		Temperature offset from the desired temperature trip point
+		above which the integral term of the power allocator
+		governor's PID controller starts accumulating errors. For
+		example, if integral_cutoff is 0, then the integral term only
+		accumulates error when temperature is above the desired
+		temperature trip point. For more information see
+		Documentation/driver-api/thermal/power_allocator.rst
+
+		Unit: millidegree Celsius
+
+		RW, Optional
+
+What:		/sys/class/thermal/thermal_zoneX/slope
+Description:
+		The slope constant used in a linear extrapolation model
+		to determine a hotspot temperature based off the sensor's
+		raw readings. It is up to the device driver to determine
+		the usage of these values.
+
+		RW, Optional
+
+What:		/sys/class/thermal/thermal_zoneX/offset
+Description:
+		The offset constant used in a linear extrapolation model
+		to determine a hotspot temperature based off the sensor's
+		raw readings. It is up to the device driver to determine
+		the usage of these values.
+
+		RW, Optional
+
+What:		/sys/class/thermal/thermal_zoneX/sustainable_power
+Description:
+		An estimate of the sustained power that can be dissipated by
+		the thermal zone. Used by the power allocator governor. For
+		more information see
+		Documentation/driver-api/thermal/power_allocator.rst
+
+		Unit: milliwatts
+
+		RW, Optional
+
+What:		/sys/class/thermal/cooling_deviceX/type
+Description:
+		String which represents the type of device, e.g:
+
+		- for generic ACPI: should be "Fan", "Processor" or "LCD"
+		- for memory controller device on intel_menlow platform:
+		  should be "Memory controller".
+
+		RO, Required
+
+What:		/sys/class/thermal/cooling_deviceX/max_state
+Description:
+		The maximum permissible cooling state of this cooling device.
+
+		RO, Required
+
+What:		/sys/class/thermal/cooling_deviceX/cur_state
+Description:
+		The current cooling state of this cooling device.
+		The value can any integer numbers between 0 and max_state:
+
+		- cur_state == 0 means no cooling
+		- cur_state == max_state means the maximum cooling.
+
+		RW, Required
+
+What:		/sys/class/thermal/cooling_deviceX/stats/reset
+Description:
+		Writing any value resets the cooling device's statistics.
+
+		WO, Required
+
+What:		/sys/class/thermal/cooling_deviceX/stats/time_in_state_ms:
+Description:
+		The amount of time spent by the cooling device in various
+		cooling states. The output will have "<state> <time>" pair
+		in each line, which will mean this cooling device spent <time>
+		msec of time at <state>.
+
+		Output will have one line for each of the supported states.
+
+		RO, Required
+
+What:		/sys/class/thermal/cooling_deviceX/stats/total_trans
+Description:
+		A single positive value showing the total number of times
+		the state of a cooling device is changed.
+
+		RO, Required
+
+What:		/sys/class/thermal/cooling_deviceX/stats/trans_table
+Description:
+		This gives fine grained information about all the cooling state
+		transitions. The cat output here is a two dimensional matrix,
+		where an entry <i,j> (row i, column j) represents the number
+		of transitions from State_i to State_j. If the transition
+		table is bigger than PAGE_SIZE, reading this will return
+		an -EFBIG error.
+
+		RO, Required