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, 367 insertions, 0 deletions

diff --git a/drivers/acpi/acpi_memhotplug.c b/drivers/acpi/acpi_memhotplug.c
new file mode 100644
index 000000000..1d7dfe4ee
--- /dev/null
+++ b/drivers/acpi/acpi_memhotplug.c
@@ -0,0 +1,367 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2004, 2013 Intel Corporation
+ * Author: Naveen B S <naveen.b.s@intel.com>
+ * Author: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
+ *
+ * All rights reserved.
+ *
+ * ACPI based HotPlug driver that supports Memory Hotplug
+ * This driver fields notifications from firmware for memory add
+ * and remove operations and alerts the VM of the affected memory
+ * ranges.
+ */
+
+#include <linux/acpi.h>
+#include <linux/memory.h>
+#include <linux/memory_hotplug.h>
+
+#include "internal.h"
+
+#define ACPI_MEMORY_DEVICE_HID			"PNP0C80"
+
+static const struct acpi_device_id memory_device_ids[] = {
+	{ACPI_MEMORY_DEVICE_HID, 0},
+	{"", 0},
+};
+
+#ifdef CONFIG_ACPI_HOTPLUG_MEMORY
+
+static int acpi_memory_device_add(struct acpi_device *device,
+				  const struct acpi_device_id *not_used);
+static void acpi_memory_device_remove(struct acpi_device *device);
+
+static struct acpi_scan_handler memory_device_handler = {
+	.ids = memory_device_ids,
+	.attach = acpi_memory_device_add,
+	.detach = acpi_memory_device_remove,
+	.hotplug = {
+		.enabled = true,
+	},
+};
+
+struct acpi_memory_info {
+	struct list_head list;
+	u64 start_addr;		/* Memory Range start physical addr */
+	u64 length;		/* Memory Range length */
+	unsigned short caching;	/* memory cache attribute */
+	unsigned short write_protect;	/* memory read/write attribute */
+	unsigned int enabled:1;
+};
+
+struct acpi_memory_device {
+	struct acpi_device *device;
+	struct list_head res_list;
+	int mgid;
+};
+
+static acpi_status
+acpi_memory_get_resource(struct acpi_resource *resource, void *context)
+{
+	struct acpi_memory_device *mem_device = context;
+	struct acpi_resource_address64 address64;
+	struct acpi_memory_info *info, *new;
+	acpi_status status;
+
+	status = acpi_resource_to_address64(resource, &address64);
+	if (ACPI_FAILURE(status) ||
+	    (address64.resource_type != ACPI_MEMORY_RANGE))
+		return AE_OK;
+
+	list_for_each_entry(info, &mem_device->res_list, list) {
+		/* Can we combine the resource range information? */
+		if ((info->caching == address64.info.mem.caching) &&
+		    (info->write_protect == address64.info.mem.write_protect) &&
+		    (info->start_addr + info->length == address64.address.minimum)) {
+			info->length += address64.address.address_length;
+			return AE_OK;
+		}
+	}
+
+	new = kzalloc_obj(struct acpi_memory_info);
+	if (!new)
+		return AE_ERROR;
+
+	INIT_LIST_HEAD(&new->list);
+	new->caching = address64.info.mem.caching;
+	new->write_protect = address64.info.mem.write_protect;
+	new->start_addr = address64.address.minimum;
+	new->length = address64.address.address_length;
+	list_add_tail(&new->list, &mem_device->res_list);
+
+	return AE_OK;
+}
+
+static void
+acpi_memory_free_device_resources(struct acpi_memory_device *mem_device)
+{
+	struct acpi_memory_info *info, *n;
+
+	list_for_each_entry_safe(info, n, &mem_device->res_list, list)
+		kfree(info);
+	INIT_LIST_HEAD(&mem_device->res_list);
+}
+
+static int
+acpi_memory_get_device_resources(struct acpi_memory_device *mem_device)
+{
+	acpi_status status;
+
+	if (!list_empty(&mem_device->res_list))
+		return 0;
+
+	status = acpi_walk_resources(mem_device->device->handle, METHOD_NAME__CRS,
+				     acpi_memory_get_resource, mem_device);
+	if (ACPI_FAILURE(status)) {
+		acpi_memory_free_device_resources(mem_device);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int acpi_memory_check_device(struct acpi_memory_device *mem_device)
+{
+	unsigned long long current_status;
+
+	/* Get device present/absent information from the _STA */
+	if (ACPI_FAILURE(acpi_evaluate_integer(mem_device->device->handle,
+					       METHOD_NAME__STA, NULL,
+					       &current_status)))
+		return -ENODEV;
+	/*
+	 * Check for device status. Device should be
+	 * present/enabled/functioning.
+	 */
+	if (!((current_status & ACPI_STA_DEVICE_PRESENT)
+	      && (current_status & ACPI_STA_DEVICE_ENABLED)
+	      && (current_status & ACPI_STA_DEVICE_FUNCTIONING)))
+		return -ENODEV;
+
+	return 0;
+}
+
+static int acpi_bind_memblk(struct memory_block *mem, void *arg)
+{
+	return acpi_bind_one(&mem->dev, arg);
+}
+
+static int acpi_bind_memory_blocks(struct acpi_memory_info *info,
+				   struct acpi_device *adev)
+{
+	return walk_memory_blocks(info->start_addr, info->length, adev,
+				  acpi_bind_memblk);
+}
+
+static int acpi_unbind_memblk(struct memory_block *mem, void *arg)
+{
+	acpi_unbind_one(&mem->dev);
+	return 0;
+}
+
+static void acpi_unbind_memory_blocks(struct acpi_memory_info *info)
+{
+	walk_memory_blocks(info->start_addr, info->length, NULL,
+			   acpi_unbind_memblk);
+}
+
+static int acpi_memory_enable_device(struct acpi_memory_device *mem_device)
+{
+	acpi_handle handle = mem_device->device->handle;
+	mhp_t mhp_flags = MHP_NID_IS_MGID;
+	int result, num_enabled = 0;
+	struct acpi_memory_info *info;
+	u64 total_length = 0;
+	int node, mgid;
+
+	node = acpi_get_node(handle);
+
+	list_for_each_entry(info, &mem_device->res_list, list) {
+		if (!info->length)
+			continue;
+		/* We want a single node for the whole memory group */
+		if (node < 0)
+			node = memory_add_physaddr_to_nid(info->start_addr);
+		total_length += info->length;
+	}
+
+	if (!total_length) {
+		dev_err(&mem_device->device->dev, "device is empty\n");
+		return -EINVAL;
+	}
+
+	mgid = memory_group_register_static(node, PFN_UP(total_length));
+	if (mgid < 0)
+		return mgid;
+	mem_device->mgid = mgid;
+
+	/*
+	 * Tell the VM there is more memory here...
+	 * Note: Assume that this function returns zero on success
+	 * We don't have memory-hot-add rollback function,now.
+	 * (i.e. memory-hot-remove function)
+	 */
+	list_for_each_entry(info, &mem_device->res_list, list) {
+		/*
+		 * If the memory block size is zero, please ignore it.
+		 * Don't try to do the following memory hotplug flowchart.
+		 */
+		if (!info->length)
+			continue;
+
+		mhp_flags |= MHP_MEMMAP_ON_MEMORY;
+		result = __add_memory(mgid, info->start_addr, info->length,
+				      mhp_flags);
+
+		/*
+		 * If the memory block has been used by the kernel, add_memory()
+		 * returns -EEXIST. If add_memory() returns the other error, it
+		 * means that this memory block is not used by the kernel.
+		 */
+		if (result && result != -EEXIST)
+			continue;
+
+		result = acpi_bind_memory_blocks(info, mem_device->device);
+		if (result) {
+			acpi_unbind_memory_blocks(info);
+			return -ENODEV;
+		}
+
+		info->enabled = 1;
+
+		/*
+		 * Add num_enable even if add_memory() returns -EEXIST, so the
+		 * device is bound to this driver.
+		 */
+		num_enabled++;
+	}
+	if (!num_enabled) {
+		dev_err(&mem_device->device->dev, "add_memory failed\n");
+		return -EINVAL;
+	}
+	/*
+	 * Sometimes the memory device will contain several memory blocks.
+	 * When one memory block is hot-added to the system memory, it will
+	 * be regarded as a success.
+	 * Otherwise if the last memory block can't be hot-added to the system
+	 * memory, it will be failure and the memory device can't be bound with
+	 * driver.
+	 */
+	return 0;
+}
+
+static void acpi_memory_remove_memory(struct acpi_memory_device *mem_device)
+{
+	struct acpi_memory_info *info, *n;
+
+	list_for_each_entry_safe(info, n, &mem_device->res_list, list) {
+		if (!info->enabled)
+			continue;
+
+		acpi_unbind_memory_blocks(info);
+		__remove_memory(info->start_addr, info->length);
+		list_del(&info->list);
+		kfree(info);
+	}
+}
+
+static void acpi_memory_device_free(struct acpi_memory_device *mem_device)
+{
+	if (!mem_device)
+		return;
+
+	/* In case we succeeded adding *some* memory, unregistering fails. */
+	if (mem_device->mgid >= 0)
+		memory_group_unregister(mem_device->mgid);
+
+	acpi_memory_free_device_resources(mem_device);
+	mem_device->device->driver_data = NULL;
+	kfree(mem_device);
+}
+
+static int acpi_memory_device_add(struct acpi_device *device,
+				  const struct acpi_device_id *not_used)
+{
+	struct acpi_memory_device *mem_device;
+	int result;
+
+	if (!device)
+		return -EINVAL;
+
+	mem_device = kzalloc_obj(struct acpi_memory_device);
+	if (!mem_device)
+		return -ENOMEM;
+
+	INIT_LIST_HEAD(&mem_device->res_list);
+	mem_device->device = device;
+	mem_device->mgid = -1;
+	device->driver_data = mem_device;
+
+	/* Get the range from the _CRS */
+	result = acpi_memory_get_device_resources(mem_device);
+	if (result) {
+		device->driver_data = NULL;
+		kfree(mem_device);
+		return result;
+	}
+
+	result = acpi_memory_check_device(mem_device);
+	if (result) {
+		acpi_memory_device_free(mem_device);
+		return 0;
+	}
+
+	result = acpi_memory_enable_device(mem_device);
+	if (result) {
+		dev_err(&device->dev, "acpi_memory_enable_device() error\n");
+		acpi_memory_device_free(mem_device);
+		return result;
+	}
+
+	dev_dbg(&device->dev, "Memory device configured by ACPI\n");
+	return 1;
+}
+
+static void acpi_memory_device_remove(struct acpi_device *device)
+{
+	struct acpi_memory_device *mem_device;
+
+	if (!device || !acpi_driver_data(device))
+		return;
+
+	mem_device = acpi_driver_data(device);
+	acpi_memory_remove_memory(mem_device);
+	acpi_memory_device_free(mem_device);
+}
+
+static bool __initdata acpi_no_memhotplug;
+
+void __init acpi_memory_hotplug_init(void)
+{
+	if (acpi_no_memhotplug) {
+		memory_device_handler.attach = NULL;
+		acpi_scan_add_handler(&memory_device_handler);
+		return;
+	}
+	acpi_scan_add_handler_with_hotplug(&memory_device_handler, "memory");
+}
+
+static int __init disable_acpi_memory_hotplug(char *str)
+{
+	acpi_no_memhotplug = true;
+	return 1;
+}
+__setup("acpi_no_memhotplug", disable_acpi_memory_hotplug);
+
+#else
+
+static struct acpi_scan_handler memory_device_handler = {
+	.ids = memory_device_ids,
+};
+
+void __init acpi_memory_hotplug_init(void)
+{
+	acpi_scan_add_handler(&memory_device_handler);
+}
+
+#endif /* CONFIG_ACPI_HOTPLUG_MEMORY */