CVE-2026-74622 in Linux
Summary
by MITRE • 08/22/2026
In the Linux kernel, the following vulnerability has been resolved:
net: atlantic: free RX pages of consumed but not refilled buffers
aq_ring_rx_deinit() only walks [sw_head, sw_tail), the region posted to
hardware. Since the page reuse strategy was added, a cleaned RX buffer keeps its page (and its DMA mapping) in the ring for reuse, and refill is batched: aq_ring_rx_fill() returns early until AQ_CFG_RX_REFILL_THRES slots are free. Slots that were consumed but not yet reposted therefore sit in the complementary [sw_tail, sw_head) gap with a live page, and
the deinit walk never visits them: up to a refill batch worth of pages and DMA mappings leak on every interface down.
Walk the whole ring instead and release whatever is still there. Also bail out if the buffer ring is already gone: a partial aq_ptp_ring_alloc() failure frees the ring but leaves aq_nic set, so aq_ptp_ring_deinit() still gets here on the unwind path.
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Analysis
by VulDB Data Team • 08/22/2026
The vulnerability identified in the Linux kernel network driver for Atlantic adapters represents a resource management flaw within the receive buffer handling logic. Specifically, the function responsible for deinitializing the RX ring fails to properly release memory resources associated with buffers that have been consumed by the hardware but not yet refilled by the software. This issue stems from an incorrect iteration range used during cleanup operations. The original implementation of aq_ring_rx_deinit only iterates over the region defined as [sw_head, sw_tail), which corresponds strictly to the slots currently posted and active in the hardware ring buffer. However, due to recent optimizations involving page reuse strategies, cleaned RX buffers retain their associated memory pages and DMA mappings within the ring structure for potential future use rather than being immediately freed. The refill process is batched, meaning that aq_ring_rx_fill returns early if fewer slots are free than required by the AQ_CFG_RX_REFILL_THRES threshold. Consequently, any buffer slots located in the complementary gap between sw_tail and sw_head remain occupied with live pages and active DMA mappings but fall outside the scope of the deinitialization loop.
This architectural oversight results in a memory leak that occurs every time the network interface is brought down or uninitialized. Up to an entire batch worth of RX buffers, along with their associated kernel page structures and DMA mapping resources, are left unreleased during this process. Over time, particularly on systems where interfaces are frequently cycled up and down, these leaks can accumulate significantly. The persistence of unused pages in the kernel memory pool reduces available system RAM and consumes DMA address space, which is a finite resource on many architectures. In severe cases, such continuous leakage could contribute to system instability or denial of service conditions as the kernel struggles to allocate new resources for active network operations due to fragmented or exhausted memory pools.
From a security perspective, this flaw aligns with CWE-401, which describes missing release of memory after effective lifetime, and falls under the broader category of resource exhaustion vulnerabilities. While primarily affecting system stability rather than directly enabling privilege escalation or remote code execution in its current state, unchecked resource leaks are often precursors to more severe issues such as kernel panics or exploitable race conditions if other parts of the driver interact with these dangling references incorrectly. The vulnerability also relates to CWE-754, improper check for unusual or exceptional conditions, specifically regarding the handling of partial allocation failures during ring initialization which can leave the system in an inconsistent state where deinitialization is attempted on a partially constructed structure.
The remediation involves modifying the cleanup logic within the driver to ensure comprehensive resource release regardless of the current buffer status. The fix requires walking the entire ring buffer rather than just the active hardware portion, ensuring that all pages and DMA mappings are properly unmapped and freed even if they reside in the refill gap. Additionally, the patch introduces a safeguard check to detect when the buffer ring has already been deallocated due to partial initialization failures. This prevents null pointer dereferences or undefined behavior during the unwind path of error handling routines where aq_ptp_ring_alloc might fail partway through, leaving the nic structure set but the actual ring memory freed. By addressing both the leak in normal operation and the potential crash scenario during failure paths, the update restores robustness to the network driver's lifecycle management.
To mitigate this issue on affected systems, administrators should apply the latest kernel updates that include the fix for the Atlantic network driver. Until patches are available, minimizing unnecessary interface cycling can reduce the rate of resource consumption, though it does not eliminate the underlying leak. Monitoring system memory usage and DMA mapping statistics may help identify early signs of excessive leakage in high-throughput or frequently reconfigured environments. Long-term mitigation strategies should include regular kernel maintenance schedules to ensure that such low-level driver defects are promptly addressed before they impact production stability.