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, 531 insertions, 0 deletions

diff --git a/drivers/md/dm-vdo/admin-state.c b/drivers/md/dm-vdo/admin-state.c
new file mode 100644
index 000000000..da153fef0
--- /dev/null
+++ b/drivers/md/dm-vdo/admin-state.c
@@ -0,0 +1,531 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright 2023 Red Hat
+ */
+
+#include "admin-state.h"
+
+#include "logger.h"
+#include "memory-alloc.h"
+#include "permassert.h"
+
+#include "completion.h"
+#include "types.h"
+
+static const struct admin_state_code VDO_CODE_NORMAL_OPERATION = {
+	.name = "VDO_ADMIN_STATE_NORMAL_OPERATION",
+	.normal = true,
+};
+const struct admin_state_code *VDO_ADMIN_STATE_NORMAL_OPERATION = &VDO_CODE_NORMAL_OPERATION;
+static const struct admin_state_code VDO_CODE_OPERATING = {
+	.name = "VDO_ADMIN_STATE_OPERATING",
+	.normal = true,
+	.operating = true,
+};
+const struct admin_state_code *VDO_ADMIN_STATE_OPERATING = &VDO_CODE_OPERATING;
+static const struct admin_state_code VDO_CODE_FORMATTING = {
+	.name = "VDO_ADMIN_STATE_FORMATTING",
+	.operating = true,
+	.loading = true,
+};
+const struct admin_state_code *VDO_ADMIN_STATE_FORMATTING = &VDO_CODE_FORMATTING;
+static const struct admin_state_code VDO_CODE_PRE_LOADING = {
+	.name = "VDO_ADMIN_STATE_PRE_LOADING",
+	.operating = true,
+	.loading = true,
+};
+const struct admin_state_code *VDO_ADMIN_STATE_PRE_LOADING = &VDO_CODE_PRE_LOADING;
+static const struct admin_state_code VDO_CODE_PRE_LOADED = {
+	.name = "VDO_ADMIN_STATE_PRE_LOADED",
+};
+const struct admin_state_code *VDO_ADMIN_STATE_PRE_LOADED = &VDO_CODE_PRE_LOADED;
+static const struct admin_state_code VDO_CODE_LOADING = {
+	.name = "VDO_ADMIN_STATE_LOADING",
+	.normal = true,
+	.operating = true,
+	.loading = true,
+};
+const struct admin_state_code *VDO_ADMIN_STATE_LOADING = &VDO_CODE_LOADING;
+static const struct admin_state_code VDO_CODE_LOADING_FOR_RECOVERY = {
+	.name = "VDO_ADMIN_STATE_LOADING_FOR_RECOVERY",
+	.operating = true,
+	.loading = true,
+};
+const struct admin_state_code *VDO_ADMIN_STATE_LOADING_FOR_RECOVERY =
+	&VDO_CODE_LOADING_FOR_RECOVERY;
+static const struct admin_state_code VDO_CODE_LOADING_FOR_REBUILD = {
+	.name = "VDO_ADMIN_STATE_LOADING_FOR_REBUILD",
+	.operating = true,
+	.loading = true,
+};
+const struct admin_state_code *VDO_ADMIN_STATE_LOADING_FOR_REBUILD = &VDO_CODE_LOADING_FOR_REBUILD;
+static const struct admin_state_code VDO_CODE_WAITING_FOR_RECOVERY = {
+	.name = "VDO_ADMIN_STATE_WAITING_FOR_RECOVERY",
+	.operating = true,
+};
+const struct admin_state_code *VDO_ADMIN_STATE_WAITING_FOR_RECOVERY =
+	&VDO_CODE_WAITING_FOR_RECOVERY;
+static const struct admin_state_code VDO_CODE_NEW = {
+	.name = "VDO_ADMIN_STATE_NEW",
+	.quiescent = true,
+};
+const struct admin_state_code *VDO_ADMIN_STATE_NEW = &VDO_CODE_NEW;
+static const struct admin_state_code VDO_CODE_INITIALIZED = {
+	.name = "VDO_ADMIN_STATE_INITIALIZED",
+};
+const struct admin_state_code *VDO_ADMIN_STATE_INITIALIZED = &VDO_CODE_INITIALIZED;
+static const struct admin_state_code VDO_CODE_RECOVERING = {
+	.name = "VDO_ADMIN_STATE_RECOVERING",
+	.draining = true,
+	.operating = true,
+};
+const struct admin_state_code *VDO_ADMIN_STATE_RECOVERING = &VDO_CODE_RECOVERING;
+static const struct admin_state_code VDO_CODE_REBUILDING = {
+	.name = "VDO_ADMIN_STATE_REBUILDING",
+	.draining = true,
+	.operating = true,
+};
+const struct admin_state_code *VDO_ADMIN_STATE_REBUILDING = &VDO_CODE_REBUILDING;
+static const struct admin_state_code VDO_CODE_SAVING = {
+	.name = "VDO_ADMIN_STATE_SAVING",
+	.draining = true,
+	.quiescing = true,
+	.operating = true,
+};
+const struct admin_state_code *VDO_ADMIN_STATE_SAVING = &VDO_CODE_SAVING;
+static const struct admin_state_code VDO_CODE_SAVED = {
+	.name = "VDO_ADMIN_STATE_SAVED",
+	.quiescent = true,
+};
+const struct admin_state_code *VDO_ADMIN_STATE_SAVED = &VDO_CODE_SAVED;
+static const struct admin_state_code VDO_CODE_SCRUBBING = {
+	.name = "VDO_ADMIN_STATE_SCRUBBING",
+	.draining = true,
+	.loading = true,
+	.operating = true,
+};
+const struct admin_state_code *VDO_ADMIN_STATE_SCRUBBING = &VDO_CODE_SCRUBBING;
+static const struct admin_state_code VDO_CODE_SAVE_FOR_SCRUBBING = {
+	.name = "VDO_ADMIN_STATE_SAVE_FOR_SCRUBBING",
+	.draining = true,
+	.operating = true,
+};
+const struct admin_state_code *VDO_ADMIN_STATE_SAVE_FOR_SCRUBBING = &VDO_CODE_SAVE_FOR_SCRUBBING;
+static const struct admin_state_code VDO_CODE_STOPPING = {
+	.name = "VDO_ADMIN_STATE_STOPPING",
+	.draining = true,
+	.quiescing = true,
+	.operating = true,
+};
+const struct admin_state_code *VDO_ADMIN_STATE_STOPPING = &VDO_CODE_STOPPING;
+static const struct admin_state_code VDO_CODE_STOPPED = {
+	.name = "VDO_ADMIN_STATE_STOPPED",
+	.quiescent = true,
+};
+const struct admin_state_code *VDO_ADMIN_STATE_STOPPED = &VDO_CODE_STOPPED;
+static const struct admin_state_code VDO_CODE_SUSPENDING = {
+	.name = "VDO_ADMIN_STATE_SUSPENDING",
+	.draining = true,
+	.quiescing = true,
+	.operating = true,
+};
+const struct admin_state_code *VDO_ADMIN_STATE_SUSPENDING = &VDO_CODE_SUSPENDING;
+static const struct admin_state_code VDO_CODE_SUSPENDED = {
+	.name = "VDO_ADMIN_STATE_SUSPENDED",
+	.quiescent = true,
+};
+const struct admin_state_code *VDO_ADMIN_STATE_SUSPENDED = &VDO_CODE_SUSPENDED;
+static const struct admin_state_code VDO_CODE_SUSPENDED_OPERATION = {
+	.name = "VDO_ADMIN_STATE_SUSPENDED_OPERATION",
+	.operating = true,
+};
+const struct admin_state_code *VDO_ADMIN_STATE_SUSPENDED_OPERATION = &VDO_CODE_SUSPENDED_OPERATION;
+static const struct admin_state_code VDO_CODE_RESUMING = {
+	.name = "VDO_ADMIN_STATE_RESUMING",
+	.operating = true,
+};
+const struct admin_state_code *VDO_ADMIN_STATE_RESUMING = &VDO_CODE_RESUMING;
+
+/**
+ * get_next_state() - Determine the state which should be set after a given operation completes
+ *                    based on the operation and the current state.
+ * @state: The current admin state.
+ * @operation: The operation to be started.
+ *
+ * Return: The state to set when the operation completes or NULL if the operation can not be
+ *         started in the current state.
+ */
+static const struct admin_state_code *get_next_state(const struct admin_state *state,
+						     const struct admin_state_code *operation)
+{
+	const struct admin_state_code *code = vdo_get_admin_state_code(state);
+
+	if (code->operating)
+		return NULL;
+
+	if (operation == VDO_ADMIN_STATE_SAVING)
+		return (code == VDO_ADMIN_STATE_NORMAL_OPERATION ? VDO_ADMIN_STATE_SAVED : NULL);
+
+	if (operation == VDO_ADMIN_STATE_SUSPENDING) {
+		return (code == VDO_ADMIN_STATE_NORMAL_OPERATION
+			? VDO_ADMIN_STATE_SUSPENDED
+			: NULL);
+	}
+
+	if (operation == VDO_ADMIN_STATE_STOPPING)
+		return (code == VDO_ADMIN_STATE_NORMAL_OPERATION ? VDO_ADMIN_STATE_STOPPED : NULL);
+
+	if (operation == VDO_ADMIN_STATE_PRE_LOADING)
+		return (code == VDO_ADMIN_STATE_INITIALIZED ? VDO_ADMIN_STATE_PRE_LOADED : NULL);
+
+	if (operation == VDO_ADMIN_STATE_SUSPENDED_OPERATION) {
+		return (((code == VDO_ADMIN_STATE_SUSPENDED) ||
+			 (code == VDO_ADMIN_STATE_SAVED)) ? code : NULL);
+	}
+
+	return VDO_ADMIN_STATE_NORMAL_OPERATION;
+}
+
+/**
+ * vdo_finish_operation() - Finish the current operation.
+ * @state: The current admin state.
+ * @result: The result of the operation.
+ *
+ * Will notify the operation waiter if there is one. This method should be used for operations
+ * started with vdo_start_operation(). For operations which were started with vdo_start_draining(),
+ * use vdo_finish_draining() instead.
+ *
+ * Return: true if there was an operation to finish.
+ */
+bool vdo_finish_operation(struct admin_state *state, int result)
+{
+	if (!vdo_get_admin_state_code(state)->operating)
+		return false;
+
+	state->complete = state->starting;
+	if (state->waiter != NULL)
+		vdo_set_completion_result(state->waiter, result);
+
+	if (!state->starting) {
+		vdo_set_admin_state_code(state, state->next_state);
+		if (state->waiter != NULL)
+			vdo_launch_completion(vdo_forget(state->waiter));
+	}
+
+	return true;
+}
+
+/**
+ * begin_operation() - Begin an operation if it may be started given the current state.
+ * @state: The current admin state.
+ * @operation: The operation to be started.
+ * @waiter: A completion to notify when the operation is complete; may be NULL.
+ * @initiator: The vdo_admin_initiator_fn to call if the operation may begin; may be NULL.
+ *
+ * Return: VDO_SUCCESS or an error.
+ */
+static int __must_check begin_operation(struct admin_state *state,
+					const struct admin_state_code *operation,
+					struct vdo_completion *waiter,
+					vdo_admin_initiator_fn initiator)
+{
+	int result;
+	const struct admin_state_code *next_state = get_next_state(state, operation);
+
+	if (next_state == NULL) {
+		result = vdo_log_error_strerror(VDO_INVALID_ADMIN_STATE,
+						"Can't start %s from %s",
+						operation->name,
+						vdo_get_admin_state_code(state)->name);
+	} else if (state->waiter != NULL) {
+		result = vdo_log_error_strerror(VDO_COMPONENT_BUSY,
+						"Can't start %s with extant waiter",
+						operation->name);
+	} else {
+		state->waiter = waiter;
+		state->next_state = next_state;
+		vdo_set_admin_state_code(state, operation);
+		if (initiator != NULL) {
+			state->starting = true;
+			initiator(state);
+			state->starting = false;
+			if (state->complete)
+				vdo_finish_operation(state, VDO_SUCCESS);
+		}
+
+		return VDO_SUCCESS;
+	}
+
+	if (waiter != NULL)
+		vdo_continue_completion(waiter, result);
+
+	return result;
+}
+
+/**
+ * start_operation() - Start an operation if it may be started given the current state.
+ * @state: The current admin state.
+ * @operation: The operation to be started.
+ * @waiter: A completion to notify when the operation is complete; may be NULL.
+ * @initiator: The vdo_admin_initiator_fn to call if the operation may begin; may be NULL.
+ *
+ * Return: true if the operation was started.
+ */
+static inline bool __must_check start_operation(struct admin_state *state,
+						const struct admin_state_code *operation,
+						struct vdo_completion *waiter,
+						vdo_admin_initiator_fn initiator)
+{
+	return (begin_operation(state, operation, waiter, initiator) == VDO_SUCCESS);
+}
+
+/**
+ * check_code() - Check the result of a state validation.
+ * @valid: True if the code is of an appropriate type.
+ * @code: The code which failed to be of the correct type.
+ * @what: What the code failed to be, for logging.
+ * @waiter: The completion to notify of the error; may be NULL.
+ *
+ * If the result failed, log an invalid state error and, if there is a waiter, notify it.
+ *
+ * Return: The result of the check.
+ */
+static bool check_code(bool valid, const struct admin_state_code *code, const char *what,
+		       struct vdo_completion *waiter)
+{
+	int result;
+
+	if (valid)
+		return true;
+
+	result = vdo_log_error_strerror(VDO_INVALID_ADMIN_STATE,
+					"%s is not a %s", code->name, what);
+	if (waiter != NULL)
+		vdo_continue_completion(waiter, result);
+
+	return false;
+}
+
+/**
+ * assert_vdo_drain_operation() - Check that an operation is a drain.
+ * @operation: The operation to check.
+ * @waiter: The completion to finish with an error if the operation is not a drain.
+ *
+ * Return: true if the specified operation is a drain.
+ */
+static bool __must_check assert_vdo_drain_operation(const struct admin_state_code *operation,
+						    struct vdo_completion *waiter)
+{
+	return check_code(operation->draining, operation, "drain operation", waiter);
+}
+
+/**
+ * vdo_start_draining() - Initiate a drain operation if the current state permits it.
+ * @state: The current admin state.
+ * @operation: The type of drain to initiate.
+ * @waiter: The completion to notify when the drain is complete.
+ * @initiator: The vdo_admin_initiator_fn to call if the operation may begin; may be NULL.
+ *
+ * Return: true if the drain was initiated, if not the waiter will be notified.
+ */
+bool vdo_start_draining(struct admin_state *state,
+			const struct admin_state_code *operation,
+			struct vdo_completion *waiter, vdo_admin_initiator_fn initiator)
+{
+	const struct admin_state_code *code = vdo_get_admin_state_code(state);
+
+	if (!assert_vdo_drain_operation(operation, waiter))
+		return false;
+
+	if (code->quiescent) {
+		vdo_launch_completion(waiter);
+		return false;
+	}
+
+	if (!code->normal) {
+		vdo_log_error_strerror(VDO_INVALID_ADMIN_STATE, "can't start %s from %s",
+				       operation->name, code->name);
+		vdo_continue_completion(waiter, VDO_INVALID_ADMIN_STATE);
+		return false;
+	}
+
+	return start_operation(state, operation, waiter, initiator);
+}
+
+/**
+ * vdo_finish_draining() - Finish a drain operation if one was in progress.
+ * @state: The current admin state.
+ *
+ * Return: true if the state was draining; will notify the waiter if so.
+ */
+bool vdo_finish_draining(struct admin_state *state)
+{
+	return vdo_finish_draining_with_result(state, VDO_SUCCESS);
+}
+
+/**
+ * vdo_finish_draining_with_result() - Finish a drain operation with a status code.
+ * @state: The current admin state.
+ * @result: The result of the drain operation.
+ *
+ * Return: true if the state was draining; will notify the waiter if so.
+ */
+bool vdo_finish_draining_with_result(struct admin_state *state, int result)
+{
+	return (vdo_is_state_draining(state) && vdo_finish_operation(state, result));
+}
+
+/**
+ * vdo_assert_load_operation() - Check that an operation is a load.
+ * @operation: The operation to check.
+ * @waiter: The completion to finish with an error if the operation is not a load.
+ *
+ * Return: true if the specified operation is a load.
+ */
+bool vdo_assert_load_operation(const struct admin_state_code *operation,
+			       struct vdo_completion *waiter)
+{
+	return check_code(operation->loading, operation, "load operation", waiter);
+}
+
+/**
+ * vdo_start_loading() - Initiate a load operation if the current state permits it.
+ * @state: The current admin state.
+ * @operation: The type of load to initiate.
+ * @waiter: The completion to notify when the load is complete; may be NULL.
+ * @initiator: The vdo_admin_initiator_fn to call if the operation may begin; may be NULL.
+ *
+ * Return: true if the load was initiated, if not the waiter will be notified.
+ */
+bool vdo_start_loading(struct admin_state *state,
+		       const struct admin_state_code *operation,
+		       struct vdo_completion *waiter, vdo_admin_initiator_fn initiator)
+{
+	return (vdo_assert_load_operation(operation, waiter) &&
+		start_operation(state, operation, waiter, initiator));
+}
+
+/**
+ * vdo_finish_loading() - Finish a load operation if one was in progress.
+ * @state: The current admin state.
+ *
+ * Return: true if the state was loading; will notify the waiter if so.
+ */
+bool vdo_finish_loading(struct admin_state *state)
+{
+	return vdo_finish_loading_with_result(state, VDO_SUCCESS);
+}
+
+/**
+ * vdo_finish_loading_with_result() - Finish a load operation with a status code.
+ * @state: The current admin state.
+ * @result: The result of the load operation.
+ *
+ * Return: true if the state was loading; will notify the waiter if so.
+ */
+bool vdo_finish_loading_with_result(struct admin_state *state, int result)
+{
+	return (vdo_is_state_loading(state) && vdo_finish_operation(state, result));
+}
+
+/**
+ * assert_vdo_resume_operation() - Check whether an admin_state_code is a resume operation.
+ * @operation: The operation to check.
+ * @waiter: The completion to notify if the operation is not a resume operation; may be NULL.
+ *
+ * Return: true if the code is a resume operation.
+ */
+static bool __must_check assert_vdo_resume_operation(const struct admin_state_code *operation,
+						     struct vdo_completion *waiter)
+{
+	return check_code(operation == VDO_ADMIN_STATE_RESUMING, operation,
+			  "resume operation", waiter);
+}
+
+/**
+ * vdo_start_resuming() - Initiate a resume operation if the current state permits it.
+ * @state: The current admin state.
+ * @operation: The type of resume to start.
+ * @waiter: The completion to notify when the resume is complete; may be NULL.
+ * @initiator: The vdo_admin_initiator_fn to call if the operation may begin; may be NULL.
+ *
+ * Return: true if the resume was initiated, if not the waiter will be notified.
+ */
+bool vdo_start_resuming(struct admin_state *state,
+			const struct admin_state_code *operation,
+			struct vdo_completion *waiter, vdo_admin_initiator_fn initiator)
+{
+	return (assert_vdo_resume_operation(operation, waiter) &&
+		start_operation(state, operation, waiter, initiator));
+}
+
+/**
+ * vdo_finish_resuming() - Finish a resume operation if one was in progress.
+ * @state: The current admin state.
+ *
+ * Return: true if the state was resuming; will notify the waiter if so.
+ */
+bool vdo_finish_resuming(struct admin_state *state)
+{
+	return vdo_finish_resuming_with_result(state, VDO_SUCCESS);
+}
+
+/**
+ * vdo_finish_resuming_with_result() - Finish a resume operation with a status code.
+ * @state: The current admin state.
+ * @result: The result of the resume operation.
+ *
+ * Return: true if the state was resuming; will notify the waiter if so.
+ */
+bool vdo_finish_resuming_with_result(struct admin_state *state, int result)
+{
+	return (vdo_is_state_resuming(state) && vdo_finish_operation(state, result));
+}
+
+/**
+ * vdo_resume_if_quiescent() - Change the state to normal operation if the current state is
+ *                             quiescent.
+ * @state: The current admin state.
+ *
+ * Return: VDO_SUCCESS if the state resumed, VDO_INVALID_ADMIN_STATE otherwise.
+ */
+int vdo_resume_if_quiescent(struct admin_state *state)
+{
+	if (!vdo_is_state_quiescent(state))
+		return VDO_INVALID_ADMIN_STATE;
+
+	vdo_set_admin_state_code(state, VDO_ADMIN_STATE_NORMAL_OPERATION);
+	return VDO_SUCCESS;
+}
+
+/**
+ * vdo_start_operation() - Attempt to start an operation.
+ * @state: The current admin state.
+ * @operation: The operation to attempt to start.
+ *
+ * Return: VDO_SUCCESS if the operation was started, VDO_INVALID_ADMIN_STATE if not
+ */
+int vdo_start_operation(struct admin_state *state,
+			const struct admin_state_code *operation)
+{
+	return vdo_start_operation_with_waiter(state, operation, NULL, NULL);
+}
+
+/**
+ * vdo_start_operation_with_waiter() - Attempt to start an operation.
+ * @state: The current admin state.
+ * @operation: The operation to attempt to start.
+ * @waiter: The completion to notify when the operation completes or fails to start; may be NULL.
+ * @initiator: The vdo_admin_initiator_fn to call if the operation may begin; may be NULL.
+ *
+ * Return: VDO_SUCCESS if the operation was started, VDO_INVALID_ADMIN_STATE if not
+ */
+int vdo_start_operation_with_waiter(struct admin_state *state,
+				    const struct admin_state_code *operation,
+				    struct vdo_completion *waiter,
+				    vdo_admin_initiator_fn initiator)
+{
+	return (check_code(operation->operating, operation, "operation", waiter) ?
+		begin_operation(state, operation, waiter, initiator) :
+		VDO_INVALID_ADMIN_STATE);
+}