CVE-2016-10906 in Linux
Summary
by MITRE
An issue was discovered in drivers/net/ethernet/arc/emac_main.c in the Linux kernel before 4.5. A use-after-free is caused by a race condition between the functions arc_emac_tx and arc_emac_tx_clean.
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Analysis
by VulDB Data Team • 08/12/2025
The vulnerability identified as CVE-2016-10906 represents a critical use-after-free flaw in the Linux kernel's Ethernet MAC driver for ARC processors. This issue resides within the drivers/net/ethernet/arc/emac_main.c file and affects kernel versions prior to 4.5. The flaw stems from a race condition that occurs between two critical functions: arc_emac_tx and arc_emac_tx_clean. The race condition creates a scenario where memory allocated for network packet transmission can be freed while still being referenced by the transmission cleaning function, leading to potentially exploitable memory corruption.
The technical nature of this vulnerability aligns with CWE-416, which specifically addresses use-after-free conditions in software systems. This type of vulnerability occurs when a program continues to reference memory after it has been freed, creating opportunities for attackers to manipulate memory contents or execute arbitrary code. The race condition between arc_emac_tx and arc_emac_tx_clean demonstrates a classic concurrency flaw where proper synchronization mechanisms are missing between these two functions that handle network packet transmission and cleanup operations. The timing of these operations creates a window where freed memory can be accessed, potentially allowing privilege escalation or denial of service attacks.
From an operational perspective, this vulnerability poses significant risks to systems utilizing ARC-based network hardware, particularly those running older Linux kernel versions. The attack surface includes any system that uses the ARC Ethernet MAC driver, which may be found in embedded systems, network appliances, or specialized hardware platforms. The exploitation of this flaw could result in complete system compromise, as attackers could leverage the use-after-free condition to execute malicious code with kernel-level privileges. The vulnerability is particularly concerning because it affects the core networking functionality of affected systems, potentially leading to network disruption or unauthorized access to sensitive system resources.
The mitigation strategy for CVE-2016-10906 primarily involves upgrading to Linux kernel version 4.5 or later, where the race condition has been resolved through proper synchronization mechanisms. System administrators should prioritize this update across all affected deployments, particularly in production environments where network reliability and security are paramount. Additionally, implementing proper access controls and network segmentation can help limit the potential impact if an attacker were to exploit this vulnerability. The fix typically involves adding appropriate locking mechanisms or atomic operations to ensure that memory allocation and deallocation occur in a synchronized manner between the transmission and cleanup functions. Organizations should also conduct thorough testing of kernel updates to ensure compatibility with existing network hardware configurations and applications. This vulnerability serves as a reminder of the critical importance of maintaining up-to-date kernel versions and proper concurrency control mechanisms in operating system drivers, particularly those handling critical network operations that could be targeted by sophisticated attackers.