CVE-2022-47946 in Linux
Summary
by MITRE • 12/24/2022
An issue was discovered in the Linux kernel 5.10.x before 5.10.155. A use-after-free in io_sqpoll_wait_sq in fs/io_uring.c allows an attacker to crash the kernel, resulting in denial of service. finish_wait can be skipped. An attack can occur in some situations by forking a process and then quickly terminating it. NOTE: later kernel versions, such as the 5.15 longterm series, substantially changed the implementation of io_sqpoll_wait_sq.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 05/19/2025
The vulnerability identified as CVE-2022-47946 represents a critical use-after-free condition within the Linux kernel's io_uring subsystem, specifically affecting versions 5.10.x prior to 5.10.155. This flaw exists in the fs/io_uring.c file within the io_sqpoll_wait_sq function, which handles synchronous I/O operations for the io_uring interface. The issue stems from improper memory management where a kernel object is accessed after it has been freed, creating a potential pathway for system instability and denial of service attacks. The vulnerability manifests when the finish_wait function is skipped during the execution flow, leaving memory in an inconsistent state that can be exploited by malicious actors.
The technical exploitation of this vulnerability relies on specific process management patterns involving forking and rapid termination of processes within the io_uring context. Attackers can trigger the use-after-free condition by creating a forked process and immediately terminating it, which causes the kernel to skip necessary cleanup operations in the io_sqpoll_wait_sq function. This particular pattern leverages the timing-sensitive nature of kernel memory management, where race conditions between process lifecycle events and I/O operation completion can result in dangling pointers being dereferenced. The vulnerability is classified under CWE-416 as a use-after-free error, which represents a common but dangerous class of memory safety issues in kernel space where freed memory regions are accessed after deallocation, potentially leading to arbitrary code execution or system crashes.
The operational impact of CVE-2022-47946 extends beyond simple denial of service, as kernel crashes can result in complete system instability and potential data loss. When the use-after-free condition is successfully exploited, it can cause the kernel to panic and reboot the system, disrupting all running services and potentially leading to uncommitted data loss. This vulnerability particularly affects systems heavily reliant on io_uring for high-performance I/O operations, including database servers, web servers, and other applications that utilize the io_uring interface for asynchronous I/O processing. The attack vector is relatively straightforward for skilled adversaries who can craft processes that exploit the timing conditions necessary to trigger the memory corruption, making this vulnerability a significant concern for production systems running affected kernel versions.
Mitigation strategies for CVE-2022-47946 primarily focus on kernel version upgrades to 5.10.155 or later, which contain the necessary fixes for the io_uring implementation. System administrators should prioritize patching affected systems, particularly those running kernel versions in the 5.10.x series prior to the fixed release. Organizations should also consider implementing monitoring for unusual process forking and termination patterns that might indicate exploitation attempts. The fix implemented in later kernel versions addresses the root cause by ensuring proper synchronization and cleanup operations within the io_sqpoll_wait_sq function, preventing the finish_wait function from being skipped under normal execution conditions. Additionally, system hardening measures such as disabling unnecessary io_uring usage and implementing proper process monitoring can provide additional defense-in-depth layers, though the primary recommendation remains the timely application of kernel security patches as outlined in the ATT&CK framework's mitigation strategies for kernel-level vulnerabilities.