CVE-2022-2585 in Linux
Summary
by MITRE • 01/08/2024
It was discovered that when exec'ing from a non-leader thread, armed POSIX CPU timers would be left on a list but freed, leading to a use-after-free.
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Analysis
by VulDB Data Team • 05/18/2025
The vulnerability described in CVE-2022-2585 represents a critical use-after-free condition within the Linux kernel's POSIX CPU timer implementation. This flaw manifests when processes execute system calls from non-leader threads, creating a scenario where timer resources become improperly managed during cleanup operations. The vulnerability specifically affects the kernel's handling of CPU timers that are armed and subsequently freed, leading to memory corruption that can be exploited by malicious actors. The issue stems from the improper synchronization and resource management between different threads within the same process, particularly when the execution context transitions from a non-leader thread to a leader thread during system call execution.
The technical root cause of this vulnerability lies in the kernel's timer subsystem where armed POSIX CPU timers are maintained on linked lists for tracking purposes. When a process executes from a non-leader thread, the timer management logic fails to properly remove the timer from its tracking list before attempting to free the associated memory structures. This creates a situation where the timer structure exists in memory but is no longer properly referenced, yet the kernel's cleanup routines still attempt to access the freed memory. The use-after-free condition occurs because the timer list management code does not properly validate that the timer has been completely removed from all tracking mechanisms before memory deallocation, resulting in a dangling pointer that can be accessed or overwritten by subsequent operations.
The operational impact of this vulnerability extends beyond simple memory corruption, as it presents a potential pathway for privilege escalation and system compromise. An attacker who can control execution from a non-leader thread and manipulate POSIX CPU timer operations could potentially exploit this flaw to execute arbitrary code with kernel privileges. The vulnerability is particularly concerning because it operates within the kernel's core timer management functionality, which is extensively used by various system processes and applications. The use-after-free condition can lead to unpredictable behavior including system crashes, data corruption, or more seriously, code execution primitives that could be leveraged to gain unauthorized access to system resources. This vulnerability affects systems running Linux kernel versions that implement POSIX CPU timer functionality, particularly those that support multi-threaded applications where non-leader thread execution is common.
Mitigation strategies for CVE-2022-2585 should focus on kernel updates and system hardening measures to prevent exploitation. The primary remediation involves applying the patched kernel version that addresses the timer management logic and ensures proper synchronization between thread contexts during timer operations. System administrators should prioritize updating affected systems to the latest kernel releases that contain the fix for this vulnerability. Additionally, monitoring for suspicious timer-related system calls and thread execution patterns can help detect potential exploitation attempts. The vulnerability aligns with CWE-416, which specifically addresses use-after-free conditions in software systems, and may be mapped to ATT&CK technique T1059.003 for execution through system services or kernel modules. Organizations should also implement process isolation measures and limit the execution of potentially malicious code from non-leader threads to reduce the attack surface. Regular security audits of kernel modules and system call handling routines can help identify similar race conditions that may exist in other parts of the kernel's resource management subsystem.