CVE-2022-1048 in Linux
Summary
by MITRE • 04/29/2022
A use-after-free flaw was found in the Linux kernel’s sound subsystem in the way a user triggers concurrent calls of PCM hw_params. The hw_free ioctls or similar race condition happens inside ALSA PCM for other ioctls. This flaw allows a local user to crash 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-2022-1048 represents a critical use-after-free flaw within the Linux kernel's sound subsystem, specifically affecting the Advanced Linux Sound Architecture (ALSA) PCM (Pulse Code Modulation) implementation. This issue manifests when a user triggers concurrent calls to PCM hw_params ioctls, creating a race condition that exists within the ALSA PCM framework for various ioctls. The flaw resides in the kernel's handling of audio device operations where memory management becomes inconsistent during concurrent access scenarios, making it a particularly dangerous vulnerability for system security.
The technical nature of this vulnerability stems from improper synchronization mechanisms within the kernel's audio subsystem. When multiple concurrent processes attempt to manipulate PCM hardware parameters simultaneously, the kernel fails to properly manage memory allocation and deallocation sequences. This race condition creates a scenario where freed memory locations may still be referenced by other processes or threads, leading to unpredictable behavior. The use-after-free condition occurs because the kernel does not adequately protect shared resources during the hw_free ioctl operations, which are fundamental operations for managing audio hardware resources. This flaw is categorized under CWE-416 as a use-after-free vulnerability, which represents a well-known class of memory safety issues that frequently lead to system instability or privilege escalation.
From an operational impact perspective, this vulnerability poses significant risks to Linux systems since it can be exploited by local users to either crash the system or potentially escalate privileges. The local privilege escalation aspect makes this particularly concerning as it allows attackers with minimal system access to gain higher-level privileges, potentially compromising the entire system. The vulnerability affects systems running affected kernel versions where the ALSA PCM subsystem handles concurrent audio operations, which is common in multimedia environments, servers processing audio streams, or any system with active audio device management. The crash potential can lead to denial of service conditions that may be exploited for persistent system disruption, while the privilege escalation capability could enable attackers to gain root access to the compromised system.
The exploitation of this vulnerability requires a local user with access to audio devices or the ability to trigger concurrent PCM operations, which is relatively straightforward in many system configurations. Attackers can leverage this flaw by creating race conditions through carefully timed concurrent calls to PCM hw_params ioctls, causing memory corruption that may result in kernel crashes or privilege escalation. This vulnerability aligns with ATT&CK technique T1068, which covers 'Exploitation for Privilege Escalation' and demonstrates how kernel-level vulnerabilities can be exploited to gain elevated system privileges. The attack surface is particularly broad given that most Linux systems with audio capabilities are potentially affected, making this a widespread concern across various deployment scenarios from desktop environments to server configurations.
Mitigation strategies for CVE-2022-1048 primarily involve applying kernel updates from respective distributions, as vendors have released patches addressing the race condition in the ALSA PCM subsystem. System administrators should prioritize patching affected systems and monitor for any signs of exploitation attempts. Additional protective measures include restricting user access to audio devices where possible, implementing proper access controls, and monitoring system logs for unusual patterns of audio device access or kernel-level anomalies. Organizations should also consider implementing network segmentation and privilege separation to limit the potential impact of successful exploitation. The vulnerability highlights the importance of proper kernel memory management and synchronization mechanisms, particularly in subsystems handling concurrent operations. Regular security audits of kernel components, especially those dealing with hardware interaction and concurrent access patterns, should be conducted to identify similar race conditions that could lead to privilege escalation or system instability.