From: Hans de Goede <hdegoede@xxxxxxxxxx> 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@xxxxxxxxxx> Signed-off-by: Bob Moore <robert.moore@xxxxxxxxx> Signed-off-by: Erik Kaneda <erik.kaneda@xxxxxxxxx> --- drivers/acpi/acpica/acobject.h | 1 + drivers/acpi/acpica/evhandler.c | 7 ++++ drivers/acpi/acpica/evregion.c | 64 ++++++++++++++++++++++++--------- drivers/acpi/acpica/evxfregn.c | 2 ++ 4 files changed, 57 insertions(+), 17 deletions(-) diff --git a/drivers/acpi/acpica/acobject.h b/drivers/acpi/acpica/acobject.h index af47a3ffd2a4..9db5ae0f79ea 100644 --- a/drivers/acpi/acpica/acobject.h +++ b/drivers/acpi/acpica/acobject.h @@ -284,6 +284,7 @@ struct acpi_object_addr_handler { acpi_adr_space_handler handler; struct acpi_namespace_node *node; /* Parent device */ void *context; + acpi_mutex context_mutex; acpi_adr_space_setup setup; union acpi_operand_object *region_list; /* Regions using this handler */ union acpi_operand_object *next; diff --git a/drivers/acpi/acpica/evhandler.c b/drivers/acpi/acpica/evhandler.c index ea9485e6a475..c0cd7147a5a3 100644 --- a/drivers/acpi/acpica/evhandler.c +++ b/drivers/acpi/acpica/evhandler.c @@ -489,6 +489,13 @@ acpi_ev_install_space_handler(struct acpi_namespace_node *node, /* Init handler obj */ + status = + acpi_os_create_mutex(&handler_obj->address_space.context_mutex); + if (ACPI_FAILURE(status)) { + acpi_ut_remove_reference(handler_obj); + goto unlock_and_exit; + } + handler_obj->address_space.space_id = (u8)space_id; handler_obj->address_space.handler_flags = flags; handler_obj->address_space.region_list = NULL; diff --git a/drivers/acpi/acpica/evregion.c b/drivers/acpi/acpica/evregion.c index 3ed7d9ae95cf..2a3c13e97555 100644 --- a/drivers/acpi/acpica/evregion.c +++ b/drivers/acpi/acpica/evregion.c @@ -112,6 +112,8 @@ acpi_ev_address_space_dispatch(union acpi_operand_object *region_obj, union acpi_operand_object *region_obj2; void *region_context = NULL; struct acpi_connection_info *context; + acpi_mutex context_mutex; + u8 context_locked; acpi_physical_address address; ACPI_FUNCTION_TRACE(ev_address_space_dispatch); @@ -136,6 +138,8 @@ acpi_ev_address_space_dispatch(union acpi_operand_object *region_obj, } context = handler_desc->address_space.context; + context_mutex = handler_desc->address_space.context_mutex; + context_locked = FALSE; /* * It may be the case that the region has never been initialized. @@ -204,6 +208,23 @@ acpi_ev_address_space_dispatch(union acpi_operand_object *region_obj, handler = handler_desc->address_space.handler; address = (region_obj->region.address + region_offset); + ACPI_DEBUG_PRINT((ACPI_DB_OPREGION, + "Handler %p (@%p) Address %8.8X%8.8X [%s]\n", + ®ion_obj->region.handler->address_space, handler, + ACPI_FORMAT_UINT64(address), + acpi_ut_get_region_name(region_obj->region. + space_id))); + + if (!(handler_desc->address_space.handler_flags & + ACPI_ADDR_HANDLER_DEFAULT_INSTALLED)) { + /* + * For handlers other than the default (supplied) handlers, we must + * exit the interpreter because the handler *might* block -- we don't + * know what it will do, so we can't hold the lock on the interpreter. + */ + acpi_ex_exit_interpreter(); + } + /* * Special handling for generic_serial_bus and general_purpose_io: * There are three extra parameters that must be passed to the @@ -212,6 +233,11 @@ acpi_ev_address_space_dispatch(union acpi_operand_object *region_obj, * 2) Length of the above buffer * 3) Actual access length from the access_as() op * + * Since we pass these extra parameters via the context, which is + * shared between threads, we must lock the context to avoid these + * parameters being changed from another thread before the handler + * has completed running. + * * In addition, for general_purpose_io, the Address and bit_width fields * are defined as follows: * 1) Address is the pin number index of the field (bit offset from @@ -221,6 +247,14 @@ acpi_ev_address_space_dispatch(union acpi_operand_object *region_obj, if ((region_obj->region.space_id == ACPI_ADR_SPACE_GSBUS) && context && field_obj) { + status = + acpi_os_acquire_mutex(context_mutex, ACPI_WAIT_FOREVER); + if (ACPI_FAILURE(status)) { + goto re_enter_interpreter; + } + + context_locked = TRUE; + /* Get the Connection (resource_template) buffer */ context->connection = field_obj->field.resource_buffer; @@ -230,6 +264,14 @@ acpi_ev_address_space_dispatch(union acpi_operand_object *region_obj, if ((region_obj->region.space_id == ACPI_ADR_SPACE_GPIO) && context && field_obj) { + status = + acpi_os_acquire_mutex(context_mutex, ACPI_WAIT_FOREVER); + if (ACPI_FAILURE(status)) { + goto re_enter_interpreter; + } + + context_locked = TRUE; + /* Get the Connection (resource_template) buffer */ context->connection = field_obj->field.resource_buffer; @@ -239,28 +281,15 @@ acpi_ev_address_space_dispatch(union acpi_operand_object *region_obj, bit_width = field_obj->field.bit_length; } - ACPI_DEBUG_PRINT((ACPI_DB_OPREGION, - "Handler %p (@%p) Address %8.8X%8.8X [%s]\n", - ®ion_obj->region.handler->address_space, handler, - ACPI_FORMAT_UINT64(address), - acpi_ut_get_region_name(region_obj->region. - space_id))); - - if (!(handler_desc->address_space.handler_flags & - ACPI_ADDR_HANDLER_DEFAULT_INSTALLED)) { - /* - * For handlers other than the default (supplied) handlers, we must - * exit the interpreter because the handler *might* block -- we don't - * know what it will do, so we can't hold the lock on the interpreter. - */ - acpi_ex_exit_interpreter(); - } - /* Call the handler */ status = handler(function, address, bit_width, value, context, region_obj2->extra.region_context); + if (context_locked) { + acpi_os_release_mutex(context_mutex); + } + if (ACPI_FAILURE(status)) { ACPI_EXCEPTION((AE_INFO, status, "Returned by Handler for [%s]", acpi_ut_get_region_name(region_obj->region. @@ -277,6 +306,7 @@ acpi_ev_address_space_dispatch(union acpi_operand_object *region_obj, } } +re_enter_interpreter: if (!(handler_desc->address_space.handler_flags & ACPI_ADDR_HANDLER_DEFAULT_INSTALLED)) { /* diff --git a/drivers/acpi/acpica/evxfregn.c b/drivers/acpi/acpica/evxfregn.c index 7672d70da850..b1ff0a8f9c14 100644 --- a/drivers/acpi/acpica/evxfregn.c +++ b/drivers/acpi/acpica/evxfregn.c @@ -201,6 +201,8 @@ acpi_remove_address_space_handler(acpi_handle device, /* 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; } -- 2.29.2
