CVE-2022-49639: 
Linux Kernel vulnerability analysis and mitigation

CVE-2022-49639 affects the Linux kernel's CIPSO (Commercial IP Security Option) implementation. The vulnerability involves data races around sysctl variables in the CIPSO module. When reading cipso sysctl variables, they can be changed concurrently, leading to potential race conditions. This issue was discovered in the Linux kernel's cipso_ipv4.c file and traces back to the original 'engine' implementation (Kernel Commit).

The vulnerability exists in the Linux kernel's CIPSO implementation where several sysctl variables (cipsov4cacheenabled, cipsov4cachebucketsize, cipsov4rbmoptfmt, and cipsov4rbmstrictvalid) could be accessed without proper synchronization. The fix involves adding READ_ONCE() operations to prevent data races when accessing these variables. The CVSS score for this vulnerability is 4.7 (Medium) (Ubuntu Security).

The vulnerability could lead to data races in the CIPSO label cache system, which is used for IP security option handling in the Linux kernel. This could potentially affect the reliability of CIPSO label mappings and security option processing (Kernel Commit).

The issue has been fixed in various Linux kernel versions through patches that implement proper synchronization using READ_ONCE(). The fix has been backported to multiple kernel versions and distributions. For Ubuntu, fixes have been applied to several kernel versions including 4.15.0-194.205 for 18.04 LTS and 4.15.0-1142.154 for AWS kernels (Ubuntu Security).