CVE-2022-49805 in Linux
Summary
by MITRE • 05/01/2025
In the Linux kernel, the following vulnerability has been resolved:
net: lan966x: Fix potential null-ptr-deref in lan966x_stats_init()
lan966x_stats_init() calls create_singlethread_workqueue() and not checked the ret value, which may return NULL. And a null-ptr-deref may happen:
lan966x_stats_init() create_singlethread_workqueue() # failed, lan966x->stats_queue is NULL queue_delayed_work() queue_delayed_work_on() __queue_delayed_work() # warning here, but continue __queue_work() # access wq->flags, null-ptr-deref
Check the ret value and return -ENOMEM if it is NULL.
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Analysis
by VulDB Data Team • 11/07/2025
The vulnerability identified as CVE-2022-49805 resides within the Linux kernel's networking subsystem, specifically affecting the lan966x driver implementation. This issue represents a classic null pointer dereference scenario that occurs during the initialization phase of network statistics handling. The lan966x driver is designed to support specific Ethernet switch hardware, and its statistics initialization function demonstrates a critical oversight in error handling that could lead to system instability or exploitation. The vulnerability manifests when the driver attempts to create a workqueue for statistics processing without validating the return value from the underlying kernel function.
The technical flaw stems from the lan966x_stats_init() function's failure to properly validate the return value from create_singlethread_workqueue() call. This kernel function can return NULL when memory allocation fails or when system resources are insufficient to create the requested workqueue. The driver proceeds to use the potentially NULL pointer in subsequent operations, particularly when queue_delayed_work() is invoked. The execution flow demonstrates a cascading failure where the initial NULL return value from create_singlethread_workqueue() eventually leads to a null pointer dereference when the kernel's workqueue subsystem attempts to access wq->flags. This represents a fundamental violation of defensive programming practices and constitutes a CWE-476 Null Pointer Dereference vulnerability.
The operational impact of this vulnerability extends beyond simple system crashes, potentially enabling privilege escalation or denial of service conditions within kernel space. When the workqueue creation fails and returns NULL, the subsequent call to queue_delayed_work() triggers the kernel's workqueue processing logic which attempts to access the NULL workqueue structure. This creates an exploitable condition that could be leveraged by malicious actors to crash the system or potentially execute arbitrary code with kernel privileges. The vulnerability affects systems running Linux kernels with the lan966x driver enabled, particularly those utilizing specific Ethernet switch hardware. From an ATT&CK perspective, this vulnerability maps to T1068 Exploitation for Privilege Escalation and T1499 Endpoint Denial of Service, as it can be used to disrupt system operations and potentially gain elevated access.
Mitigation strategies for CVE-2022-49805 require immediate kernel updates from vendors that include the proper error handling fix. The solution involves adding a validation check after create_singlethread_workqueue() to verify that the returned workqueue pointer is not NULL before proceeding with workqueue operations. This validation should return -ENOMEM to properly indicate resource allocation failure to the calling function. System administrators should prioritize patching affected systems, particularly those running embedded devices or network infrastructure that utilize the lan966x hardware. Additionally, monitoring for kernel panic messages or system instability related to workqueue operations can help detect exploitation attempts. The fix aligns with kernel security best practices by implementing proper error handling and resource validation, which prevents the propagation of NULL pointer dereference conditions throughout the kernel's subsystems. Organizations should also consider implementing network segmentation and access controls to limit potential attack vectors that could exploit this vulnerability in production environments.