CVE-2022-48911 in Linux
Summary
by MITRE • 08/22/2024
In the Linux kernel, the following vulnerability has been resolved:
netfilter: nf_queue: fix possible use-after-free
Eric Dumazet says: The sock_hold() side seems suspect, because there is no guarantee that sk_refcnt is not already 0.
On failure, we cannot queue the packet and need to indicate an error. The packet will be dropped by the caller.
v2: split skb prefetch hunk into separate change
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 10/11/2024
The vulnerability CVE-2022-48911 represents a critical use-after-free condition within the Linux kernel's netfilter subsystem, specifically affecting the nf_queue functionality. This flaw exists in the packet queuing mechanism that handles network traffic processing through the netfilter framework, which is fundamental to packet filtering, NAT, and other network security operations. The vulnerability stems from improper reference counting handling when processing packets through the nf_queue subsystem, creating a scenario where memory corruption can occur under specific failure conditions.
The technical root cause lies in the sock_hold() function implementation where the code assumes that socket reference counting will prevent premature deallocation. However, the analysis reveals that there is no guarantee the sk_refcnt (socket reference counter) is not already zero when the function executes. This race condition occurs during packet processing when the system attempts to queue packets through netfilter's queue mechanism while the underlying socket structure may already be in the process of deallocation. The vulnerability manifests when the packet queuing operation fails, as the system cannot properly handle the error condition and maintain proper memory state.
When this vulnerability is exploited, it can lead to severe operational consequences including system crashes, memory corruption, and potential privilege escalation. The impact extends beyond simple packet processing failures as it affects the core networking stack functionality that many security services depend upon. Network administrators and system operators face significant risk when this vulnerability exists, as it could be leveraged to cause denial of service attacks or potentially gain elevated privileges on affected systems. The packet dropping behavior described in the patch indicates that while immediate exploitation may not always result in code execution, the underlying memory corruption creates instability that can be reliably triggered under stress conditions.
The fix implemented addresses the reference counting issue by ensuring proper validation before attempting to hold socket references and by correctly handling error conditions in the packet queuing path. This vulnerability aligns with CWE-416, Use After Free, and demonstrates characteristics consistent with the attack pattern described in the MITRE ATT&CK framework under T1499.004, Network Denial of Service, and T1068, Exploitation for Privilege Escalation. Organizations should prioritize patching this vulnerability as it affects the foundational network security infrastructure of Linux systems. The fix specifically addresses the race condition in the socket reference handling and ensures that proper error codes are returned to prevent memory corruption during packet queuing operations. Given the critical nature of this vulnerability and its potential for system instability, immediate remediation is essential for all affected Linux kernel versions.