From c7891884a55effcf3e54e25835ef9fac39ef48f3 Mon Sep 17 00:00:00 2001 From: Armin Wolf Date: Wed, 2 Nov 2022 22:23:36 +0100 Subject: [PATCH] platform/x86: dell-ddv: Warn if ePPID has a suspicious length On some systems (like the Dell Inspiron 3505), the acpi operation region holding the ePPID string is two bytes too short, causing acpi functions like ToString() to omit the last two bytes. This does not happen on Windows, supposedly due to their implementation of ToString() ignoring buffer boundaries. Inform users if the ePPID length differs from the Dell specification so they can complain to Dell to fix their BIOS. Tested on a Dell Inspiron 3505. Signed-off-by: Armin Wolf Link: https://lore.kernel.org/r/20221102212336.380257-2-W_Armin@gmx.de Reviewed-by: Hans de Goede Signed-off-by: Hans de Goede --- drivers/platform/x86/dell/dell-wmi-ddv.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/drivers/platform/x86/dell/dell-wmi-ddv.c b/drivers/platform/x86/dell/dell-wmi-ddv.c index 1a001296e8c6..2bb449845d14 100644 --- a/drivers/platform/x86/dell/dell-wmi-ddv.c +++ b/drivers/platform/x86/dell/dell-wmi-ddv.c @@ -10,12 +10,14 @@ #include #include #include +#include #include #include #include #include #include #include +#include #include #include #include @@ -27,6 +29,9 @@ #define DELL_DDV_SUPPORTED_INTERFACE 2 #define DELL_DDV_GUID "8A42EA14-4F2A-FD45-6422-0087F7A7E608" +#define DELL_EPPID_LENGTH 20 +#define DELL_EPPID_EXT_LENGTH 23 + enum dell_ddv_method { DELL_DDV_BATTERY_DESIGN_CAPACITY = 0x01, DELL_DDV_BATTERY_FULL_CHARGE_CAPACITY = 0x02, @@ -196,6 +201,10 @@ static ssize_t eppid_show(struct device *dev, struct device_attribute *attr, cha if (ret < 0) return ret; + if (obj->string.length != DELL_EPPID_LENGTH && obj->string.length != DELL_EPPID_EXT_LENGTH) + dev_info_once(&data->wdev->dev, FW_INFO "Suspicious ePPID length (%d)\n", + obj->string.length); + ret = sysfs_emit(buf, "%s\n", obj->string.pointer); kfree(obj); -- 2.11.0