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author | Hans de Goede <hdegoede@redhat.com> | 2021-02-18 15:17:07 -0800 |
---|---|---|
committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2021-02-19 16:03:25 +0100 |
commit | c27f3d011b08540e68233cf56274fdc34bebb9b5 (patch) | |
tree | 47798aebe1d925d6ed6259872da5dffaf9350306 /drivers | |
parent | 938bdd1d7dad75299201d1cc47c1dcf4d49f9274 (diff) | |
download | linux-c27f3d011b08540e68233cf56274fdc34bebb9b5.tar.bz2 |
ACPICA: Fix race in generic_serial_bus (I2C) and GPIO op_region parameter handling
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>
Diffstat (limited to 'drivers')
-rw-r--r-- | drivers/acpi/acpica/acobject.h | 1 | ||||
-rw-r--r-- | drivers/acpi/acpica/evhandler.c | 7 | ||||
-rw-r--r-- | drivers/acpi/acpica/evregion.c | 64 | ||||
-rw-r--r-- | 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; } |