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, 279 insertions, 0 deletions

diff --git a/drivers/acpi/acpica/utcache.c b/drivers/acpi/acpica/utcache.c
new file mode 100644
index 000000000..6ec2a6e88
--- /dev/null
+++ b/drivers/acpi/acpica/utcache.c
@@ -0,0 +1,279 @@
+// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
+/******************************************************************************
+ *
+ * Module Name: utcache - local cache allocation routines
+ *
+ * Copyright (C) 2000 - 2026, Intel Corp.
+ *
+ *****************************************************************************/
+
+#include <acpi/acpi.h>
+#include "accommon.h"
+
+#define _COMPONENT          ACPI_UTILITIES
+ACPI_MODULE_NAME("utcache")
+
+#ifdef ACPI_USE_LOCAL_CACHE
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_os_create_cache
+ *
+ * PARAMETERS:  cache_name      - Ascii name for the cache
+ *              object_size     - Size of each cached object
+ *              max_depth       - Maximum depth of the cache (in objects)
+ *              return_cache    - Where the new cache object is returned
+ *
+ * RETURN:      Status
+ *
+ * DESCRIPTION: Create a cache object
+ *
+ ******************************************************************************/
+acpi_status
+acpi_os_create_cache(char *cache_name,
+		     u16 object_size,
+		     u16 max_depth, struct acpi_memory_list **return_cache)
+{
+	struct acpi_memory_list *cache;
+
+	ACPI_FUNCTION_ENTRY();
+
+	if (!cache_name || !return_cache || !object_size) {
+		return (AE_BAD_PARAMETER);
+	}
+
+	/* Create the cache object */
+
+	cache = acpi_os_allocate(sizeof(struct acpi_memory_list));
+	if (!cache) {
+		return (AE_NO_MEMORY);
+	}
+
+	/* Populate the cache object and return it */
+
+	memset(cache, 0, sizeof(struct acpi_memory_list));
+	cache->list_name = cache_name;
+	cache->object_size = object_size;
+	cache->max_depth = max_depth;
+
+	*return_cache = cache;
+	return (AE_OK);
+}
+
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_os_purge_cache
+ *
+ * PARAMETERS:  cache           - Handle to cache object
+ *
+ * RETURN:      Status
+ *
+ * DESCRIPTION: Free all objects within the requested cache.
+ *
+ ******************************************************************************/
+
+acpi_status acpi_os_purge_cache(struct acpi_memory_list *cache)
+{
+	void *next;
+	acpi_status status;
+
+	ACPI_FUNCTION_ENTRY();
+
+	if (!cache) {
+		return (AE_BAD_PARAMETER);
+	}
+
+	status = acpi_ut_acquire_mutex(ACPI_MTX_CACHES);
+	if (ACPI_FAILURE(status)) {
+		return (status);
+	}
+
+	/* Walk the list of objects in this cache */
+
+	while (cache->list_head) {
+
+		/* Delete and unlink one cached state object */
+
+		next = ACPI_GET_DESCRIPTOR_PTR(cache->list_head);
+		ACPI_FREE(cache->list_head);
+
+		cache->list_head = next;
+		cache->current_depth--;
+	}
+
+	(void)acpi_ut_release_mutex(ACPI_MTX_CACHES);
+	return (AE_OK);
+}
+
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_os_delete_cache
+ *
+ * PARAMETERS:  cache           - Handle to cache object
+ *
+ * RETURN:      Status
+ *
+ * DESCRIPTION: Free all objects within the requested cache and delete the
+ *              cache object.
+ *
+ ******************************************************************************/
+
+acpi_status acpi_os_delete_cache(struct acpi_memory_list *cache)
+{
+	acpi_status status;
+
+	ACPI_FUNCTION_ENTRY();
+
+	/* Purge all objects in the cache */
+
+	status = acpi_os_purge_cache(cache);
+	if (ACPI_FAILURE(status)) {
+		return (status);
+	}
+
+	/* Now we can delete the cache object */
+
+	acpi_os_free(cache);
+	return (AE_OK);
+}
+
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_os_release_object
+ *
+ * PARAMETERS:  cache       - Handle to cache object
+ *              object      - The object to be released
+ *
+ * RETURN:      None
+ *
+ * DESCRIPTION: Release an object to the specified cache. If cache is full,
+ *              the object is deleted.
+ *
+ ******************************************************************************/
+
+acpi_status acpi_os_release_object(struct acpi_memory_list *cache, void *object)
+{
+	acpi_status status;
+
+	ACPI_FUNCTION_ENTRY();
+
+	if (!cache || !object) {
+		return (AE_BAD_PARAMETER);
+	}
+
+	/* If cache is full, just free this object */
+
+	if (cache->current_depth >= cache->max_depth) {
+		ACPI_FREE(object);
+		ACPI_MEM_TRACKING(cache->total_freed++);
+	}
+
+	/* Otherwise put this object back into the cache */
+
+	else {
+		status = acpi_ut_acquire_mutex(ACPI_MTX_CACHES);
+		if (ACPI_FAILURE(status)) {
+			return (status);
+		}
+
+		/* Mark the object as cached */
+
+		memset(object, 0xCA, cache->object_size);
+		ACPI_SET_DESCRIPTOR_TYPE(object, ACPI_DESC_TYPE_CACHED);
+
+		/* Put the object at the head of the cache list */
+
+		ACPI_SET_DESCRIPTOR_PTR(object, cache->list_head);
+		cache->list_head = object;
+		cache->current_depth++;
+
+		(void)acpi_ut_release_mutex(ACPI_MTX_CACHES);
+	}
+
+	return (AE_OK);
+}
+
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_os_acquire_object
+ *
+ * PARAMETERS:  cache           - Handle to cache object
+ *
+ * RETURN:      the acquired object. NULL on error
+ *
+ * DESCRIPTION: Get an object from the specified cache. If cache is empty,
+ *              the object is allocated.
+ *
+ ******************************************************************************/
+
+void *acpi_os_acquire_object(struct acpi_memory_list *cache)
+{
+	acpi_status status;
+	void *object;
+
+	ACPI_FUNCTION_TRACE(os_acquire_object);
+
+	if (!cache) {
+		return_PTR(NULL);
+	}
+
+	status = acpi_ut_acquire_mutex(ACPI_MTX_CACHES);
+	if (ACPI_FAILURE(status)) {
+		return_PTR(NULL);
+	}
+
+	ACPI_MEM_TRACKING(cache->requests++);
+
+	/* Check the cache first */
+
+	if (cache->list_head) {
+
+		/* There is an object available, use it */
+
+		object = cache->list_head;
+		cache->list_head = ACPI_GET_DESCRIPTOR_PTR(object);
+
+		cache->current_depth--;
+
+		ACPI_MEM_TRACKING(cache->hits++);
+		ACPI_DEBUG_PRINT_RAW((ACPI_DB_EXEC,
+				      "%s: Object %p from %s cache\n",
+				      ACPI_GET_FUNCTION_NAME, object,
+				      cache->list_name));
+
+		status = acpi_ut_release_mutex(ACPI_MTX_CACHES);
+		if (ACPI_FAILURE(status)) {
+			return_PTR(NULL);
+		}
+
+		/* Clear (zero) the previously used Object */
+
+		memset(object, 0, cache->object_size);
+	} else {
+		/* The cache is empty, create a new object */
+
+#ifdef ACPI_DBG_TRACK_ALLOCATIONS
+		ACPI_MEM_TRACKING(cache->total_allocated++);
+
+		if ((cache->total_allocated - cache->total_freed) >
+		    cache->max_occupied) {
+			cache->max_occupied =
+			    cache->total_allocated - cache->total_freed;
+		}
+#endif
+
+		/* Avoid deadlock with ACPI_ALLOCATE_ZEROED */
+
+		status = acpi_ut_release_mutex(ACPI_MTX_CACHES);
+		if (ACPI_FAILURE(status)) {
+			return_PTR(NULL);
+		}
+
+		object = ACPI_ALLOCATE_ZEROED(cache->object_size);
+		if (!object) {
+			return_PTR(NULL);
+		}
+	}
+
+	return_PTR(object);
+}
+#endif				/* ACPI_USE_LOCAL_CACHE */