CVE-2026-90371 in Linux
Summary
by MITRE • 09/17/2026
In the Linux kernel, the following vulnerability has been resolved:
wifi: mt76: fix RXDMAD_C buffer recycling race
The RXDMAD_C buffers come from the RRO data queues' page pools, which are bound to a different NAPI, so the direct page-pool recycle used here could race the owning NAPI; take the non-direct path as is already done for WED RX queues.
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Analysis
by VulDB Data Team • 09/17/2026
The Linux kernel vulnerability identified in the mt76 wireless driver involves a concurrency flaw within the receive DMA buffer management subsystem, specifically concerning the recycling of RXDMAD_C buffers. This issue arises from an improper interaction between memory pool allocation mechanisms and network processing interrupts, leading to potential race conditions that can compromise system stability or lead to data corruption during high-throughput wireless operations. The root cause lies in how page pools are associated with Network API (NAPI) contexts for buffer recycling.
RXDMAD_C buffers originate from RRO data queues' page pools, which are bound to a specific NAPI context distinct from the one handling the current packet processing flow. When the driver attempts to recycle these buffers directly back into their respective page pools without proper synchronization relative to the owning NAPI's execution state, it creates a race condition. The direct page-pool recycling mechanism assumes exclusive access or safe concurrent modification capabilities that do not exist when multiple contexts might be accessing or modifying the pool metadata simultaneously. This lack of atomicity allows for scenarios where buffer references are corrupted, freed prematurely, or double-freed, which can result in kernel panics, memory leaks, or unpredictable network stack behavior.
From a technical perspective, this vulnerability is classified under CWE-362: Concurrent Execution using Shared Resource with Improper Synchronization (Race Condition). The flaw specifically affects the integrity of shared memory structures used for packet buffering in wireless drivers. In terms of offensive security frameworks such as MITRE ATT&CK, while not directly exploitable by an external attacker without physical or local access to trigger specific timing conditions, this type of race condition falls under techniques related to privilege escalation via kernel vulnerabilities if it leads to a denial-of-service that can be leveraged for further exploitation. It represents a failure in resource management synchronization within the operating system's network subsystem.
The operational impact of this vulnerability includes potential system crashes or freezes when the mt76 wireless adapter is subjected to heavy traffic loads, particularly during periods where buffer recycling rates are high. Network connectivity may become unstable, experiencing packet loss or latency spikes due to dropped buffers or corrupted descriptors. In severe cases, an attacker with local access could potentially trigger a denial-of-service condition by flooding the interface with packets designed to maximize race window exposure, thereby disrupting network services on the host system.
The resolution involves modifying the buffer recycling logic within the mt76 driver to avoid direct page-pool manipulation when racing against the owning NAPI context. Instead of using the direct recycle path which lacks necessary synchronization barriers relative to the RRO queue's NAPI binding, the fix implements a non-direct recycling path similar to that already established for WED (Wireless Ethernet Dispatch) RX queues. This approach ensures that buffer return operations are properly serialized or deferred in a manner consistent with the owning context's lifecycle, thereby eliminating the race condition and maintaining memory integrity during concurrent network processing tasks.
To mitigate this vulnerability, system administrators should ensure that their Linux kernels are updated to include patches addressing mt76 driver concurrency issues. For environments where immediate patching is not feasible, limiting wireless interface throughput or disabling unused Wi-Fi interfaces can reduce exposure windows. Additionally, monitoring kernel logs for oops messages related to network drivers may help detect early signs of instability caused by this race condition before it leads to a full system crash.