kernel_optimize_test/drivers/acpi/acpica/evxfregn.c
Hans de Goede 62ba6d817c ACPICA: Fix race in generic_serial_bus (I2C) and GPIO op_region parameter handling
commit c27f3d011b08540e68233cf56274fdc34bebb9b5 upstream.

ACPICA commit c9e0116952363b0fa815143dca7e9a2eb4fefa61

The handling of the generic_serial_bus (I2C) and GPIO op_regions in
acpi_ev_address_space_dispatch() passes a number of extra parameters
to the address-space handler through the address-space Context pointer
(instead of using more function parameters).

The Context is shared between threads, so if multiple threads try to
call the handler for the same address-space at the same time, then
a second thread could change the parameters of a first thread while
the handler is running for the first thread.

An example of this race hitting is the Lenovo Yoga Tablet2 1015L,
where there are both attrib_bytes accesses and attrib_byte accesses
to the same address-space. The attrib_bytes access stores the number
of bytes to transfer in Context->access_length. Where as for the
attrib_byte access the number of bytes to transfer is always 1 and
field_obj->Field.access_length is unused (so 0). Both types of
accesses racing from different threads leads to the following problem:

 1. Thread a. starts an attrib_bytes access, stores a non 0 value
    from field_obj->Field.access_length in Context->access_length

 2. Thread b. starts an attrib_byte access, stores 0 in
    Context->access_length

 3. Thread a. calls i2c_acpi_space_handler() (under Linux). Which
    sees that the access-type is ACPI_GSB_ACCESS_ATTRIB_MULTIBYTE
    and calls acpi_gsb_i2c_read_bytes(..., Context->access_length)

 4. At this point Context->access_length is 0 (set by thread b.)

rather then the field_obj->Field.access_length value from thread a.
This 0 length reads leads to the following errors being logged:

 i2c i2c-0: adapter quirk: no zero length (addr 0x0078, size 0, read)
 i2c i2c-0: i2c read 0 bytes from client@0x78 starting at reg 0x0 failed, error: -95

Note this is just an example of the problems which this race can cause.

There are likely many more (sporadic) problems caused by this race.

This commit adds a new context_mutex to struct acpi_object_addr_handler
and makes acpi_ev_address_space_dispatch() take that mutex when
using the shared Context to pass extra parameters to an address-space
handler, fixing this race.

Note the new mutex must be taken *after* exiting the interpreter,
therefor the existing acpi_ex_exit_interpreter() call is moved to above
the code which stores the extra parameters in the Context.

Link: https://github.com/acpica/acpica/commit/c9e01169
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Erik Kaneda <erik.kaneda@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-03-11 14:17:21 +01:00

231 lines
6.3 KiB
C

// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
/******************************************************************************
*
* Module Name: evxfregn - External Interfaces, ACPI Operation Regions and
* Address Spaces.
*
* Copyright (C) 2000 - 2020, Intel Corp.
*
*****************************************************************************/
#define EXPORT_ACPI_INTERFACES
#include <acpi/acpi.h>
#include "accommon.h"
#include "acnamesp.h"
#include "acevents.h"
#define _COMPONENT ACPI_EVENTS
ACPI_MODULE_NAME("evxfregn")
/*******************************************************************************
*
* FUNCTION: acpi_install_address_space_handler
*
* PARAMETERS: device - Handle for the device
* space_id - The address space ID
* handler - Address of the handler
* setup - Address of the setup function
* context - Value passed to the handler on each access
*
* RETURN: Status
*
* DESCRIPTION: Install a handler for all op_regions of a given space_id.
*
* NOTE: This function should only be called after acpi_enable_subsystem has
* been called. This is because any _REG methods associated with the Space ID
* are executed here, and these methods can only be safely executed after
* the default handlers have been installed and the hardware has been
* initialized (via acpi_enable_subsystem.)
*
******************************************************************************/
acpi_status
acpi_install_address_space_handler(acpi_handle device,
acpi_adr_space_type space_id,
acpi_adr_space_handler handler,
acpi_adr_space_setup setup, void *context)
{
struct acpi_namespace_node *node;
acpi_status status;
ACPI_FUNCTION_TRACE(acpi_install_address_space_handler);
/* Parameter validation */
if (!device) {
return_ACPI_STATUS(AE_BAD_PARAMETER);
}
status = acpi_ut_acquire_mutex(ACPI_MTX_NAMESPACE);
if (ACPI_FAILURE(status)) {
return_ACPI_STATUS(status);
}
/* Convert and validate the device handle */
node = acpi_ns_validate_handle(device);
if (!node) {
status = AE_BAD_PARAMETER;
goto unlock_and_exit;
}
/* Install the handler for all Regions for this Space ID */
status =
acpi_ev_install_space_handler(node, space_id, handler, setup,
context);
if (ACPI_FAILURE(status)) {
goto unlock_and_exit;
}
/* Run all _REG methods for this address space */
acpi_ev_execute_reg_methods(node, space_id, ACPI_REG_CONNECT);
unlock_and_exit:
(void)acpi_ut_release_mutex(ACPI_MTX_NAMESPACE);
return_ACPI_STATUS(status);
}
ACPI_EXPORT_SYMBOL(acpi_install_address_space_handler)
/*******************************************************************************
*
* FUNCTION: acpi_remove_address_space_handler
*
* PARAMETERS: device - Handle for the device
* space_id - The address space ID
* handler - Address of the handler
*
* RETURN: Status
*
* DESCRIPTION: Remove a previously installed handler.
*
******************************************************************************/
acpi_status
acpi_remove_address_space_handler(acpi_handle device,
acpi_adr_space_type space_id,
acpi_adr_space_handler handler)
{
union acpi_operand_object *obj_desc;
union acpi_operand_object *handler_obj;
union acpi_operand_object *region_obj;
union acpi_operand_object **last_obj_ptr;
struct acpi_namespace_node *node;
acpi_status status;
ACPI_FUNCTION_TRACE(acpi_remove_address_space_handler);
/* Parameter validation */
if (!device) {
return_ACPI_STATUS(AE_BAD_PARAMETER);
}
status = acpi_ut_acquire_mutex(ACPI_MTX_NAMESPACE);
if (ACPI_FAILURE(status)) {
return_ACPI_STATUS(status);
}
/* Convert and validate the device handle */
node = acpi_ns_validate_handle(device);
if (!node ||
((node->type != ACPI_TYPE_DEVICE) &&
(node->type != ACPI_TYPE_PROCESSOR) &&
(node->type != ACPI_TYPE_THERMAL) &&
(node != acpi_gbl_root_node))) {
status = AE_BAD_PARAMETER;
goto unlock_and_exit;
}
/* Make sure the internal object exists */
obj_desc = acpi_ns_get_attached_object(node);
if (!obj_desc) {
status = AE_NOT_EXIST;
goto unlock_and_exit;
}
/* Find the address handler the user requested */
handler_obj = obj_desc->common_notify.handler;
last_obj_ptr = &obj_desc->common_notify.handler;
while (handler_obj) {
/* We have a handler, see if user requested this one */
if (handler_obj->address_space.space_id == space_id) {
/* Handler must be the same as the installed handler */
if (handler_obj->address_space.handler != handler) {
status = AE_BAD_PARAMETER;
goto unlock_and_exit;
}
/* Matched space_id, first dereference this in the Regions */
ACPI_DEBUG_PRINT((ACPI_DB_OPREGION,
"Removing address handler %p(%p) for region %s "
"on Device %p(%p)\n",
handler_obj, handler,
acpi_ut_get_region_name(space_id),
node, obj_desc));
region_obj = handler_obj->address_space.region_list;
/* Walk the handler's region list */
while (region_obj) {
/*
* First disassociate the handler from the region.
*
* NOTE: this doesn't mean that the region goes away
* The region is just inaccessible as indicated to
* the _REG method
*/
acpi_ev_detach_region(region_obj, TRUE);
/*
* Walk the list: Just grab the head because the
* detach_region removed the previous head.
*/
region_obj =
handler_obj->address_space.region_list;
}
/* Remove this Handler object from the list */
*last_obj_ptr = handler_obj->address_space.next;
/* Now we can delete the handler object */
acpi_os_release_mutex(handler_obj->address_space.
context_mutex);
acpi_ut_remove_reference(handler_obj);
goto unlock_and_exit;
}
/* Walk the linked list of handlers */
last_obj_ptr = &handler_obj->address_space.next;
handler_obj = handler_obj->address_space.next;
}
/* The handler does not exist */
ACPI_DEBUG_PRINT((ACPI_DB_OPREGION,
"Unable to remove address handler %p for %s(%X), DevNode %p, obj %p\n",
handler, acpi_ut_get_region_name(space_id), space_id,
node, obj_desc));
status = AE_NOT_EXIST;
unlock_and_exit:
(void)acpi_ut_release_mutex(ACPI_MTX_NAMESPACE);
return_ACPI_STATUS(status);
}
ACPI_EXPORT_SYMBOL(acpi_remove_address_space_handler)