CVE-2023-54240 in Linux
Summary
by MITRE • 12/30/2025
In the Linux kernel, the following vulnerability has been resolved:
net: ethernet: mtk_eth_soc: fix possible NULL pointer dereference in mtk_hwlro_get_fdir_all()
rule_locs is allocated in ethtool_get_rxnfc and the size is determined by rule_cnt from user space. So rule_cnt needs to be check before using rule_locs to avoid NULL pointer dereference.
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Analysis
by VulDB Data Team • 04/27/2026
The vulnerability CVE-2023-54240 represents a critical NULL pointer dereference flaw within the MediaTek Ethernet SoC driver of the Linux kernel. This issue specifically affects the mtk_hwlro_get_fdir_all() function which handles hardware offload flow director operations. The vulnerability stems from improper validation of user-supplied parameters during ethtool operations, creating a potential pathway for denial of service or privilege escalation attacks. The flaw exists in the network subsystem of the Linux kernel, specifically within the ethernet driver framework for MediaTek SoC devices, making it a significant concern for embedded systems and network infrastructure deployments.
The technical implementation of this vulnerability occurs when the rule_locs pointer is allocated based on rule_cnt values provided by user space through ethtool_get_rxnfc calls. The function fails to validate that rule_cnt contains a legitimate positive value before attempting to access the rule_locs array. This oversight creates a scenario where a malicious user could supply a zero or negative rule_cnt value, resulting in a NULL pointer dereference when the code attempts to process what appears to be a valid array but is actually a null reference. The vulnerability manifests as a classic buffer over-read condition that can be exploited to crash the kernel or potentially escalate privileges.
The operational impact of this vulnerability extends beyond simple system crashes, as it affects the stability and reliability of network operations on devices using MediaTek Ethernet SoC hardware. Systems utilizing this driver for network management, particularly those in enterprise environments or embedded applications, could experience unexpected service interruptions when malicious or malformed ethtool commands are executed. The vulnerability affects the network subsystem's ability to properly handle flow director rules, potentially disrupting network traffic management and hardware offload operations that rely on these mechanisms for performance optimization.
Mitigation strategies for CVE-2023-54240 should focus on immediate kernel updates from vendors that include the patched version of the MediaTek Ethernet driver. System administrators should prioritize patching affected systems, particularly those running older kernel versions where this vulnerability remains unaddressed. The fix implements proper bounds checking of user-provided rule_cnt values before array access, aligning with security best practices for input validation and buffer management. Organizations should also implement monitoring for anomalous ethtool activity and consider restricting ethtool access to privileged users only. This vulnerability demonstrates the importance of proper input validation in kernel space operations and aligns with CWE-476 which addresses NULL pointer dereference issues in software security practices.
This vulnerability falls under the ATT&CK technique T1068 which covers 'Exploitation for Privilege Escalation' and T1499 which covers 'Endpoint Denial of Service'. The fix demonstrates proper defensive programming practices that align with the principle of least privilege and input validation, which are fundamental security controls recommended by NIST SP 800-53 and ISO 27001 frameworks for protecting against such kernel-level vulnerabilities. The resolution of this issue through kernel patching represents a standard remediation approach for similar vulnerabilities in network driver subsystems, emphasizing the need for regular security updates and proper code review processes in kernel development.