CVE-2022-1998 in Linux
Summary
by MITRE • 06/09/2022
A use after free in the Linux kernel File System notify functionality was found in the way user triggers copy_info_records_to_user() call to fail in copy_event_to_user(). A local user could use this flaw to crash the system or potentially escalate their privileges on the system.
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Analysis
by VulDB Data Team • 05/18/2025
The vulnerability identified as CVE-2022-1998 represents a critical use after free flaw within the Linux kernel's file system notification subsystem. This issue manifests in the specific context of the inotify functionality which provides mechanisms for monitoring file system events. The flaw occurs when a user process triggers the copy_info_records_to_user() function through a failure path in copy_event_to_user(), creating a scenario where freed memory locations are subsequently accessed or manipulated. The vulnerability is categorized under CWE-416 as a use after free condition, which represents a classic memory safety issue that can lead to system instability and potential privilege escalation. The attack vector requires local system access, making it a local privilege escalation vulnerability that could be exploited by unprivileged users to gain elevated privileges.
The technical implementation of this vulnerability involves the kernel's inotify subsystem where memory allocation and deallocation processes create a window of opportunity for exploitation. When the copy_event_to_user() function fails during its execution, it leads to an improper cleanup of memory structures that are subsequently accessed by copy_info_records_to_user(). This improper handling occurs within the kernel's memory management subsystem and specifically affects the file system notification mechanisms that are fundamental to many system operations. The flaw demonstrates poor resource management practices where freed kernel memory structures are not properly invalidated or reinitialized before being accessed again. The vulnerability is particularly concerning because it operates at the kernel level, where memory corruption can lead to immediate system crashes or more sophisticated exploitation techniques that bypass standard security mechanisms.
The operational impact of CVE-2022-1998 extends beyond simple system crashes to include potential privilege escalation capabilities that could allow attackers to gain root access to compromised systems. Local users who can execute code on a target system can leverage this vulnerability to escalate their privileges, potentially leading to complete system compromise. The vulnerability affects all Linux kernel versions that implement the inotify functionality, making it widespread across numerous distributions and system configurations. Attackers can exploit this flaw by triggering specific sequences of system calls that cause the kernel to enter the problematic code path, resulting in either immediate system instability or more sophisticated exploitation techniques. The vulnerability also relates to ATT&CK technique T1068 which involves privilege escalation through kernel exploits, and T1499 which covers network denial of service through kernel-level attacks.
Mitigation strategies for CVE-2022-1998 require immediate patching of affected kernel versions to address the memory management issue in the inotify subsystem. System administrators should prioritize applying kernel updates from their respective distribution vendors to remediate this vulnerability. Additionally, monitoring for unusual system behavior or kernel crashes that might indicate exploitation attempts can provide early warning signs of potential attacks. The vulnerability's nature as a kernel-level memory corruption issue means that traditional user-space security measures like firewalls or intrusion detection systems may not prevent exploitation, requiring kernel-level security enhancements. Organizations should also consider implementing additional security measures such as kernel hardening techniques, disabling unnecessary inotify functionality where possible, and maintaining comprehensive system monitoring to detect potential exploitation attempts. The fix implemented by kernel developers typically involves proper memory management practices that ensure freed structures are not accessed again, preventing the use after free condition that enables both system instability and privilege escalation.