CVE-2022-49198: 
Linux Kernel vulnerability analysis and mitigation

CVE-2022-49198 affects the Linux kernel's MPTCP (Multipath TCP) implementation. The vulnerability was discovered when a crash occurred during MPTCP pressure testing. The issue stems from improper initialization timing of tcptsortedanchor before releasing skb (socket buffer) in the _mptcpalloctxskb function (Kernel Git).

The vulnerability occurs in the _mptcpalloctxskb function where skb is allocated and skb->tcptsortedanchor is initialized. Under memory pressure conditions, skwmemschedule returns false, triggering a kfreeskb call. The issue arises because skb->skbrefdst is not null (sharing memory space with tcptsortedanchor), causing kfreeskb to attempt releasing dst, resulting in a system crash. This vulnerability was introduced by commit f70cad1085d1 'mptcp: stop relying on tcptxskb_cache' (Kernel Git).

When exploited, this vulnerability causes a kernel crash, leading to system instability and potential denial of service. The crash manifests as a kernel paging request error with an NX-protected page execution attempt, indicating a potential security boundary violation (Kernel Git).

The issue has been patched by adding a tcpskbtsortedanchorcleanup(skb) call before kfreeskb in the _mptcpalloctxskb function. This fix ensures proper cleanup of the tcptsorted_anchor before the memory is freed (Kernel Git).