The Linux kernel contained a use-after-free vulnerability in the module/dups component related to the lifetime handling of kmod_dup_req instances. The existing code used RCU (Read-Copy-Update) to delay freeing kmod_dup_req instances until no references remained. However, parallel users referencing these instances in kmod_dup_request_exists_wait() did not enter an RCU read-side critical section, leading to potential use-after-free conditions. The function kmod_dup_request_exists_wait() requires holding a valid reference across a blocking wait, making RCU unsuitable for this case. The issue was fixed by replacing RCU-based lifecycle management with reference counting to ensure proper memory management and prevent use-after-free.

This vulnerability allows local attackers with limited privileges to exploit a use-after-free condition, potentially leading to arbitrary code execution or denial of service due to memory corruption. The CVSS score of 7.8 reflects high impact on confidentiality, integrity, and availability.

A fix is available that replaces the RCU-based lifetime management of kmod_dup_req with reference counting. Users should apply the official Linux kernel patches that address this vulnerability. No additional mitigation steps are indicated beyond applying the fix.