Messages in this thread Patch in this message | | | Subject | Re: [PATCH 1/2] platform/x86: dell-ddv: Improve buffer handling | From | Armin Wolf <> | Date | Mon, 7 Nov 2022 22:23:36 +0100 |
| |
Am 07.11.22 um 20:49 schrieb Hans de Goede:
> Hi, > > On 11/7/22 19:54, David E. Box wrote: >> On Wed, 2022-11-02 at 22:23 +0100, Armin Wolf wrote: >>> When the DDV interface returns a buffer, it actually >>> returns a acpi buffer containing an integer (buffer size) >>> and another acpi buffer (buffer content). >>> The size of the buffer may be smaller than the size of >>> the buffer content, which is perfectly valid and should not >>> be treated as an error. >> Is there documentation for this that you can refer to?
Yes and no. With the bmf2mof tool, i was able to extract the following MOF-description of the WMI interface:
[WMI, Dynamic, Provider("WmiProv"), Locale("MS\\0x409"), Description("WMI Function"), guid("{8A42EA14-4F2A-FD45-6422-0087F7A7E608}")] class DDVWmiMethodFunction { [key, read] string InstanceName; [read] boolean Active;
[WmiMethodId(1), Implemented, read, write, Description("Return Battery Design Capacity.")] void BatteryDesignCapacity([in] uint32 arg2, [out] uint32 argr); [WmiMethodId(2), Implemented, read, write, Description("Return Battery Full Charge Capacity.")] void BatteryFullChargeCapacity([in] uint32 arg2, [out] uint32 argr); [WmiMethodId(3), Implemented, read, write, Description("Return Battery Manufacture Name.")] void BatteryManufactureName([in] uint32 arg2, [out] string argr); [WmiMethodId(4), Implemented, read, write, Description("Return Battery Manufacture Date.")] void BatteryManufactureDate([in] uint32 arg2, [out] uint32 argr); [WmiMethodId(5), Implemented, read, write, Description("Return Battery Serial Number.")] void BatterySerialNumber([in] uint32 arg2, [out] uint32 argr); [WmiMethodId(6), Implemented, read, write, Description("Return Battery Chemistry Value.")] void BatteryChemistryValue([in] uint32 arg2, [out] string argr); [WmiMethodId(7), Implemented, read, write, Description("Return Battery Temperature.")] void BatteryTemperature([in] uint32 arg2, [out] uint32 argr); [WmiMethodId(8), Implemented, read, write, Description("Return Battery Current.")] void BatteryCurrent([in] uint32 arg2, [out] uint32 argr); [WmiMethodId(9), Implemented, read, write, Description("Return Battery Voltage.")] void BatteryVoltage([in] uint32 arg2, [out] uint32 argr); [WmiMethodId(10), Implemented, read, write, Description("Return Battery Manufacture Access(MA code).")] void BatteryManufactureAceess([in] uint32 arg2, [out] uint32 argr); [WmiMethodId(11), Implemented, read, write, Description("Return Battery Relative State-Of-Charge.")] void BatteryRelativeStateOfCharge([in] uint32 arg2, [out] uint32 argr); [WmiMethodId(12), Implemented, read, write, Description("Return Battery Cycle Count")] void BatteryCycleCount([in] uint32 arg2, [out] uint32 argr); [WmiMethodId(13), Implemented, read, write, Description("Return Battery ePPID")] void BatteryePPID([in] uint32 arg2, [out] string argr); [WmiMethodId(14), Implemented, read, write, Description("Return Battery Raw Analytics Start")] void BatteryeRawAnalyticsStart([in] uint32 arg2, [out] uint32 argr); [WmiMethodId(15), Implemented, read, write, Description("Return Battery Raw Analytics")] void BatteryeRawAnalytics([in] uint32 arg2, [out] uint32 RawSize, [out, WmiSizeIs("RawSize") : ToInstance] uint8 RawData[]); [WmiMethodId(16), Implemented, read, write, Description("Return Battery Design Voltage.")] void BatteryDesignVoltage([in] uint32 arg2, [out] uint32 argr); [WmiMethodId(18), Implemented, read, write, Description("Return Version.")] void ReturnVersion([in] uint32 arg2, [out] uint32 argr); [WmiMethodId(32), Implemented, read, write, Description("Return Fan Sensor Information")] void FanSensorInformation([in] uint32 arg2, [out] uint32 RawSize, [out, WmiSizeIs("RawSize") : ToInstance] uint8 RawData[]); [WmiMethodId(34), Implemented, read, write, Description("Return Thermal Sensor Information")] void ThermalSensorInformation([in] uint32 arg2, [out] uint32 RawSize, [out, WmiSizeIs("RawSize") : ToInstance] uint8 RawData[]); };
I also found out that an "empty" fan sensor information buffer still has a content buffer length of 1, but a size integer of 0.
>>> Also use the buffer size instead of the buffer content size >>> when accessing the buffer to prevent accessing bogus data. >>> >>> Tested on a Dell Inspiron 3505. >>> >>> Signed-off-by: Armin Wolf <W_Armin@gmx.de> >>> --- >>> drivers/platform/x86/dell/dell-wmi-ddv.c | 12 +++++++----- >>> 1 file changed, 7 insertions(+), 5 deletions(-) >>> >>> diff --git a/drivers/platform/x86/dell/dell-wmi-ddv.c >>> b/drivers/platform/x86/dell/dell-wmi-ddv.c >>> index 699feae3c435..1a001296e8c6 100644 >>> --- a/drivers/platform/x86/dell/dell-wmi-ddv.c >>> +++ b/drivers/platform/x86/dell/dell-wmi-ddv.c >>> @@ -129,9 +129,9 @@ static int dell_wmi_ddv_query_buffer(struct wmi_device >>> *wdev, enum dell_ddv_meth >>> if (obj->package.elements[1].type != ACPI_TYPE_BUFFER) >>> goto err_free; >>> >>> - if (buffer_size != obj->package.elements[1].buffer.length) { >>> + if (buffer_size > obj->package.elements[1].buffer.length) { >>> dev_warn(&wdev->dev, >>> - FW_WARN "ACPI buffer size (%llu) does not match WMI >>> buffer size (%d)\n", >>> + FW_WARN "WMI buffer size (%llu) exceeds ACPI buffer >>> size (%d)\n", >>> buffer_size, obj->package.elements[1].buffer.length); >>> >>> goto err_free; >>> @@ -271,15 +271,17 @@ static int dell_wmi_ddv_buffer_read(struct seq_file >>> *seq, enum dell_ddv_method m >>> struct device *dev = seq->private; >>> struct dell_wmi_ddv_data *data = dev_get_drvdata(dev); >>> union acpi_object *obj; >>> - union acpi_object buf; >>> + u64 size; >>> + u8 *buf; >>> int ret; >>> >>> ret = dell_wmi_ddv_query_buffer(data->wdev, method, 0, &obj); >>> if (ret < 0) >>> return ret; >>> >>> - buf = obj->package.elements[1]; >>> - ret = seq_write(seq, buf.buffer.pointer, buf.buffer.length); >>> + size = obj->package.elements[0].integer.value; >>> + buf = obj->package.elements[1].buffer.pointer; >>> + ret = seq_write(seq, buf, size); >> Okay, so the buffer may provide more space than what should actually be used >> according to the size field. This looks like a bug that should have a fixes tag >> on the original commit. > I have already merged this and both the original commit as well as > this fix will land in 6.2, so I don't think a Fixes commit is > really necessary in this case. > > Also the old code checked that the 2 sizes matched, so it was more > strict and as such running only the original patch should not lead > to buffer overruns or anything like that. > > Regards, > > Hans > >
| |