CVE-2023-52864

In the Linux kernel, the following vulnerability has been resolved:

platform/x86: wmi: Fix opening of char device

Since commit fa1f68db6ca7 ("drivers: misc: pass miscdevice pointer via file private data"), the miscdevice stores a pointer to itself inside filp->private_data, which means that private_data will not be NULL when wmi_char_open() is called. This might cause memory corruption should wmi_char_open() be unable to find its driver, something which can happen when the associated WMI device is deleted in wmi_free_devices().

Fix the problem by using the miscdevice pointer to retrieve the WMI device data associated with a char device using container_of(). This also avoids wmi_char_open() picking a wrong WMI device bound to a driver with the same name as the original driver.