CVE-2021-4148 in Linux
Summary
by MITRE • 03/24/2022
A vulnerability was found in the Linux kernel's block_invalidatepage in fs/buffer.c in the filesystem. A missing sanity check may allow a local attacker with user privilege to cause a denial of service (DOS) problem.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 03/25/2022
The vulnerability identified as CVE-2021-4148 resides within the Linux kernel's block_invalidatepage function located in fs/buffer.c, representing a critical flaw in the filesystem subsystem that can be exploited by local unprivileged users. This issue stems from a missing sanity check that fails to validate input parameters properly before processing them, creating a potential pathway for malicious actors to disrupt system operations through deliberate exploitation of the kernel's buffer management mechanisms.
The technical nature of this vulnerability manifests when the block_invalidatepage function processes page invalidation requests without adequate validation of the page structure or associated data. This missing validation allows an attacker to craft specially crafted input that can trigger unexpected behavior within the kernel's memory management subsystem. The flaw operates at the kernel level where buffer operations are handled, making it particularly dangerous as it can be leveraged to cause system instability or complete system crashes without requiring elevated privileges.
From an operational standpoint, this vulnerability presents a significant denial of service risk that can be exploited by any local user with standard privileges, eliminating the need for root access or special administrative capabilities. The impact extends beyond simple service disruption as the vulnerability can potentially cause kernel oops, system panics, or complete system hangs that require manual intervention to recover from. Such an attack vector represents a serious concern for system administrators and security professionals who must consider the implications of local privilege escalation attacks that can compromise system availability and reliability.
The vulnerability aligns with CWE-129, which specifically addresses insufficient input validation, and demonstrates characteristics consistent with ATT&CK technique T1499.004 related to network denial of service. The attack surface is particularly concerning given that the flaw exists within core kernel functionality that handles buffer operations across all filesystem types, making it potentially exploitable across diverse system configurations and deployments. Organizations should consider this vulnerability as part of their broader security posture assessment, particularly in environments where local user access cannot be fully controlled or monitored.
Mitigation strategies should focus on applying the relevant kernel security patches provided by the Linux kernel development team, as these updates will contain the necessary fixes to validate input parameters before processing them within the block_invalidatepage function. Additionally, system administrators should implement monitoring solutions to detect anomalous buffer operations or kernel memory access patterns that might indicate exploitation attempts. While the vulnerability requires local user privileges to exploit, the potential for system-wide impact makes it essential for organizations to maintain up-to-date kernel versions and implement comprehensive security monitoring across their infrastructure.