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author | Hans de Goede <hdegoede@redhat.com> | 2018-11-18 22:25:35 +0300 |
---|---|---|
committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2018-11-19 13:06:09 +0300 |
commit | ae6b3e54aa52cd29965b8e4e47000ed2c5d78eb8 (patch) | |
tree | 46e3b06a01d379704d1dd62a7fed70db99c294b0 /drivers/acpi/acpica | |
parent | 9ff01193a20d391e8dbce4403dd5ef87c7eaaca6 (diff) | |
download | linux-ae6b3e54aa52cd29965b8e4e47000ed2c5d78eb8.tar.xz |
ACPICA: Fix handling of buffer-size in acpi_ex_write_data_to_field()
Generic Serial Bus transfers use a data struct like this:
struct gsb_buffer {
u8 status;
u8 len;
u8 data[0];
};
acpi_ex_write_data_to_field() copies the data which is to be written from
the source-buffer to a temp-buffer. This is done because the OpReg-handler
overwrites the status field and some transfers do a write + read-back.
Commit f99b89eefeb6 ("ACPICA: Update for generic_serial_bus and
attrib_raw_process_bytes protocol") acpi_ex_write_data_to_field()
introduces a number of problems with this:
1) It drops a "length += 2" statement used to calculate the temp-buffer
size causing the temp-buffer to only be 1/2 bytes large for byte/word
transfers while it should be 3/4 bytes (taking the status and len field
into account). This is already fixed in commit e324e10109fc ("ACPICA:
Update for field unit access") which refactors the code.
The ACPI 6.0 spec (ACPI_6.0.pdf) "5.5.2.4.5.2 Declaring and Using a
GenericSerialBusData Buffer" (page 232) states that the GenericSerialBus
Data Buffer Length field is only valid when doing a Read/Write Block
(AttribBlock) transfer, but since the troublesome commit we unconditionally
use the len field to determine how much data to copy from the source-buffer
into the temp-buffer passed to the OpRegion.
This causes 3 further issues:
2) This may lead to not copying enough data to the temp-buffer causing the
OpRegion handler for the serial-bus to write garbage to the hardware.
3) The temp-buffer passed to the OpRegion is allocated to the size
returned by acpi_ex_get_serial_access_length(), which may be as little
as 1, so potentially this may lead to a write overflow of the temp-buffer.
4) Commit e324e10109fc ("ACPICA: Update for field unit access") drops a
length check on the source-buffer, leading to a potential read overflow
of the source-buffer.
This commit fixes all 3 remaining issues by not looking at the len field at
all (the interpretation of this field is left up to the OpRegion handler),
and copying the minimum of the source- and temp-buffer sizes from the
source-buffer to the temp-buffer.
This fixes e.g. an Acer S1003 no longer booting since the troublesome
commit.
Fixes: f99b89eefeb6 (ACPICA: Update for generic_serial_bus and ...)
Fixes: e324e10109fc (ACPICA: Update for field unit access)
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/acpi/acpica')
-rw-r--r-- | drivers/acpi/acpica/exserial.c | 21 |
1 files changed, 2 insertions, 19 deletions
diff --git a/drivers/acpi/acpica/exserial.c b/drivers/acpi/acpica/exserial.c index 0d42f30e5b25..9920fac6413f 100644 --- a/drivers/acpi/acpica/exserial.c +++ b/drivers/acpi/acpica/exserial.c @@ -244,7 +244,6 @@ acpi_ex_write_serial_bus(union acpi_operand_object *source_desc, { acpi_status status; u32 buffer_length; - u32 data_length; void *buffer; union acpi_operand_object *buffer_desc; u32 function; @@ -282,14 +281,12 @@ acpi_ex_write_serial_bus(union acpi_operand_object *source_desc, case ACPI_ADR_SPACE_SMBUS: buffer_length = ACPI_SMBUS_BUFFER_SIZE; - data_length = ACPI_SMBUS_DATA_SIZE; function = ACPI_WRITE | (obj_desc->field.attribute << 16); break; case ACPI_ADR_SPACE_IPMI: buffer_length = ACPI_IPMI_BUFFER_SIZE; - data_length = ACPI_IPMI_DATA_SIZE; function = ACPI_WRITE; break; @@ -310,7 +307,6 @@ acpi_ex_write_serial_bus(union acpi_operand_object *source_desc, /* Add header length to get the full size of the buffer */ buffer_length += ACPI_SERIAL_HEADER_SIZE; - data_length = source_desc->buffer.pointer[1]; function = ACPI_WRITE | (accessor_type << 16); break; @@ -318,20 +314,6 @@ acpi_ex_write_serial_bus(union acpi_operand_object *source_desc, return_ACPI_STATUS(AE_AML_INVALID_SPACE_ID); } -#if 0 - OBSOLETE ? - /* Check for possible buffer overflow */ - if (data_length > source_desc->buffer.length) { - ACPI_ERROR((AE_INFO, - "Length in buffer header (%u)(%u) is greater than " - "the physical buffer length (%u) and will overflow", - data_length, buffer_length, - source_desc->buffer.length)); - - return_ACPI_STATUS(AE_AML_BUFFER_LIMIT); - } -#endif - /* Create the transfer/bidirectional/return buffer */ buffer_desc = acpi_ut_create_buffer_object(buffer_length); @@ -342,7 +324,8 @@ acpi_ex_write_serial_bus(union acpi_operand_object *source_desc, /* Copy the input buffer data to the transfer buffer */ buffer = buffer_desc->buffer.pointer; - memcpy(buffer, source_desc->buffer.pointer, data_length); + memcpy(buffer, source_desc->buffer.pointer, + min(buffer_length, source_desc->buffer.length)); /* Lock entire transaction if requested */ |