CVE-2025-38131: Use After Free

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

coresight: prevent deactivate active config while enabling the config

While enable active config via cscfg_csdev_enable_active_config(), active config could be deactivated via configfs' sysfs interface. This could make UAF issue in below scenario:

CPU0 CPU1 (sysfs enable) load module cscfg_load_config_sets() activate config. // sysfs (sys_active_cnt == 1) ... cscfg_csdev_enable_active_config() lock(csdev->cscfg_csdev_lock) // here load config activate by CPU1 unlock(csdev->cscfg_csdev_lock)

deactivate config // sysfs (sys_activec_cnt == 0) cscfg_unload_config_sets() unload module

// access to config_desc which freed // while unloading module. cscfg_csdev_enable_config

To address this, use cscfg_config_desc's active_cnt as a reference count which will be holded when - activate the config. - enable the activated config. and put the module reference when config_active_cnt == 0.