CVE-2026-98488 in Linux
Summary
by MITRE • 10/18/2026
In the Linux kernel, the following vulnerability has been resolved:
net: atl1e: fix soft lockup on out-of-range hw_next_to_clean read
Same issue as atl1c (see the first commit in this series, "net: atl1c: fix soft lockup on out-of-range tpd_cons read"): the hardware can report an out-of-range hw_next_to_clean (seen as 0xffff) while the PCIe link/MAC is resetting. An out-of-range value can never be reached and the loop below would spin forever. Treat it as "nothing new to clean" instead.
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Analysis
by VulDB Data Team • 10/19/2026
The vulnerability identified in the Linux kernel network driver for Atheros L1E Ethernet adapters involves a critical logic error within the packet transmission completion handling routine, specifically concerning the management of hardware descriptor rings. This issue manifests as a soft lockup, which is a condition where a CPU core becomes unresponsive because it is trapped in an infinite loop that prevents other processes from executing on that processor. The root cause lies in how the driver interprets the hw_next_to_clean index, a value provided by the network interface card hardware to indicate the next descriptor buffer available for processing completed transmission tasks. Under normal operating conditions, this index advances sequentially through the ring buffer as packets are successfully transmitted and acknowledged by the hardware. However, during specific edge cases involving PCIe link instability or MAC reset procedures, the hardware may report an anomalous value of 0xffff instead of a valid index within the allocated descriptor ring boundaries.
This out-of-range value represents a significant deviation from expected driver behavior because it falls outside the bounds of the memory-mapped array used to track packet status. When the kernel code attempts to process this invalid index, it fails to find any corresponding completion event and consequently enters an infinite loop attempting to clean up non-existent or inaccessible descriptors. This spinlock condition effectively halts all network I/O operations handled by that specific driver instance and can lead to broader system instability if not mitigated at a higher level. The problem is particularly insidious because it only occurs during transient hardware states such as link resets, making it difficult to reproduce under standard stress testing unless the physical layer connectivity is intentionally disrupted or subjected to electrical noise conditions that trigger reset cycles.
From a security and reliability perspective, this vulnerability aligns with CWE-835, which describes loops with unreachable exit conditions, often referred to as infinite loops. The failure to validate hardware input against expected bounds before processing constitutes a lack of proper boundary checks, allowing the system state to enter an unrecoverable deadlock scenario without external intervention such as a watchdog timer reset or manual kernel panic recovery. This type of flaw impacts availability by rendering network services unusable on affected systems until the machine is rebooted or the driver module is unloaded and reloaded, which may not be possible if other critical processes depend on that network interface for management traffic or storage access over IP.
The remediation strategy implemented in this fix involves adding explicit validation logic to detect when the hw_next_to_clean value exceeds valid limits, specifically checking against the 0xffff sentinel value associated with reset states. By treating these out-of-range readings as indicators that there is nothing new to clean rather than attempting to process them, the driver avoids entering the infinite loop and maintains system responsiveness even during hardware resets. This approach ensures graceful degradation of service during transient faults rather than a complete catastrophic failure of the network stack component responsible for this adapter.
In terms of industry standards mapping, this vulnerability can be associated with MITRE ATT&CK technique T1499, Endpoint Denial of Service, specifically under sub-techniques involving resource exhaustion or loop-based denial of service attacks if an attacker could artificially induce such hardware states through physical access or sophisticated electromagnetic interference. While primarily a stability issue rather than a direct exploitation vector for privilege escalation, the resulting system hang represents a significant availability risk in production environments where network continuity is critical. System administrators should ensure that kernel updates incorporating this patch are applied promptly to mitigate the risk of unplanned downtime caused by hardware reset events triggering this software defect.