CVE-2021-47194: 
Linux Kernel vulnerability analysis and mitigation

CVE-2021-47194 is a vulnerability in the Linux kernel's cfg80211 wireless networking subsystem. The issue was discovered when userspace tools switch from NL80211_IFTYPE_P2P_GO to NL80211_IFTYPE_ADHOC via send_msg(NL80211_CMD_SET_INTERFACE). The vulnerability was disclosed on April 10, 2024, and affects Linux kernel versions from 3.6.0 up to versions before 4.4.293, 4.9.291, 4.14.256, 4.19.218, and 5.15.5 (NVD).

The vulnerability occurs because the system does not call the cleanup function cfg80211_stop_ap() during the interface type switch. This leads to the initialization of in-use data, specifically affecting the sdata->assigned_chanctx_list while it is still an element of assigned_vifs list, resulting in a corrupted linked list. The vulnerability has been assigned a CVSS v3.1 Base Score of 7.8 (High) with the vector string CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H (NVD).

The vulnerability can lead to the corruption of linked lists in the kernel's wireless networking subsystem, potentially causing system instability or crashes. This improper initialization vulnerability (CWE-665) could allow a local attacker with appropriate privileges to potentially compromise the system (NVD).

The vulnerability requires local access and low privileges to exploit. It can be triggered through userspace tools that manipulate wireless interface types, specifically when switching from P2P_GO to ADHOC mode (Kernel Patch).

The vulnerability has been fixed in multiple Linux kernel versions. Updates are available for various distributions including Ubuntu 16.04 ESM, 14.04 ESM, and other affected versions. After applying the standard system update, a system reboot is required to implement all necessary changes. Users need to recompile and reinstall all third-party kernel modules they might have installed (Ubuntu Security).