CVE-2011-1478 in Linux
Summary
by MITRE
The napi_reuse_skb function in net/core/dev.c in the Generic Receive Offload (GRO) implementation in the Linux kernel before 2.6.38 does not reset the values of certain structure members, which might allow remote attackers to cause a denial of service (NULL pointer dereference) via a malformed VLAN frame.
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Analysis
by VulDB Data Team • 11/24/2021
The vulnerability identified as CVE-2011-1478 resides within the Linux kernel's Generic Receive Offload (GRO) implementation, specifically in the napi_reuse_skb function located in net/core/dev.c. This flaw represents a critical security issue that affects Linux kernel versions prior to 2.6.38, where the function fails to properly reset essential structure member values during packet processing. The vulnerability manifests when the kernel processes malformed VLAN frames, creating a scenario where remote attackers can exploit the incomplete structure cleanup to trigger system instability.
The technical nature of this vulnerability stems from improper memory management within the network packet processing pipeline. When the napi_reuse_skb function handles network packets, it reuses existing skb (socket buffer) structures to optimize performance. However, the function does not adequately reset all relevant structure members, particularly those related to packet metadata and internal state tracking. This incomplete cleanup leaves behind stale or invalid data that can persist across multiple packet processing cycles, ultimately leading to a NULL pointer dereference condition when the kernel attempts to access these improperly initialized fields.
From an operational perspective, this vulnerability creates a significant denial of service risk that can be exploited remotely through crafted VLAN frames. The attack vector requires minimal privileges and can be executed from any network location capable of sending malformed network traffic to the target system. The impact extends beyond simple service disruption, as the NULL pointer dereference can cause kernel panics, system crashes, and complete system unavailability. This makes the vulnerability particularly dangerous in production environments where system uptime and availability are critical requirements, potentially affecting network infrastructure, servers, and embedded systems running vulnerable kernel versions.
The vulnerability aligns with CWE-457: Use of Uninitialized Variable and follows patterns commonly associated with the ATT&CK technique T1499.004: Endpoint Denial of Service, where adversaries leverage kernel-level flaws to exhaust system resources or trigger critical failures. Organizations running affected kernel versions face substantial operational risk, as the vulnerability can be exploited by automated scanning tools or malicious actors without requiring special privileges or extensive knowledge of the target system. The impact is particularly severe given that many network devices and servers rely on Linux kernel functionality, making this vulnerability a widespread concern across enterprise and cloud environments.
Mitigation strategies for CVE-2011-1478 primarily involve upgrading to Linux kernel versions 2.6.38 or later, where the vulnerability has been addressed through proper structure member reset implementation. System administrators should prioritize patching affected systems, particularly those handling network traffic or serving as network infrastructure components. Additional protective measures include implementing network segmentation to limit exposure, deploying intrusion detection systems to monitor for suspicious VLAN frame patterns, and establishing robust monitoring protocols to detect potential exploitation attempts. Organizations should also consider applying kernel hardening patches and maintaining comprehensive network traffic monitoring to identify and respond to potential exploitation attempts before they can cause significant disruption.