CVE-2026-68330: net: airoha: Fix DMA direction for NPU mailbox buffer
In the Linux kernel, the following vulnerability has been resolved:
net: airoha: Fix DMA direction for NPU mailbox buffer
airohanpusendmsg() always maps the mailbox buffer with DMATODEVICE, but some callers expect the NPU to write response data back into the same buffer:
- airohanpuwlanmsgget() (NPUOPGET): NPU writes response into the buffer, then the caller reads it via memcpy() - airohanpuppestatssetup() (NPUOPSET): NPU writes back npustatsaddr field in the response
On non-cache-coherent architectures like EN7581 (Cortex-A53 without hardware cache coherency for NPU DMA), DMATODEVICE unmap is a no-op — it does not invalidate the CPU cache. If the NPU-written cache line is still present in the CPU cache when the caller reads the buffer, the CPU observes stale data instead of the NPU response.
This is a timing-sensitive bug: small mailbox buffers (~24 bytes) typically fit in a single cache line and may survive in the cache until the caller reads them, producing silent data corruption rather than a crash. The bug is more likely to trigger when the caller reads the response immediately after dmaunmapsingle() without intervening cache-evicting operations.
Fix by using DMABIDIRECTIONAL for both map and unmap, which ensures dmaunmapsingle() invalidates the CPU cache on non-coherent systems. The mailbox buffers are small so there is no performance concern.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
ubuntu/linux-aws-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1014.14~24.04.1 - Upgrade
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ubuntu/linux-azure-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1017.17~24.04.1 - Upgrade
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ubuntu/linux-azure-fde-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1016.16~24.04.1 - Upgrade
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ubuntu/linux-gcp-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1014.14~24.04.1 - Upgrade
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ubuntu/linux-hwe-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-38.38~24.04.4 - Upgrade
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ubuntu/linux-nvidia-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1024.25~24.04.1 - Upgrade
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ubuntu/linux-oracle-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1013.13~24.04.1 - Upgrade
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ubuntu/linux-riscv-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-38.38.1~24.04.1 - Upgrade
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ubuntu/linuxto a version that resolves this vulnerability.Fixed in 7.0.0-38.38 - Upgrade
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ubuntu/linux-awsto a version that resolves this vulnerability.Fixed in 7.0.0-1014.14 - Upgrade
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ubuntu/linux-azureto a version that resolves this vulnerability.Fixed in 7.0.0-1017.17 - Upgrade
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ubuntu/linux-azure-fdeto a version that resolves this vulnerability.Fixed in 7.0.0-1016.16 - Upgrade
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ubuntu/linux-gcpto a version that resolves this vulnerability.Fixed in 7.0.0-1014.14 - Upgrade
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ubuntu/linux-gketo a version that resolves this vulnerability.Fixed in 7.0.0-1008.9 - Upgrade
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ubuntu/linux-ibmto a version that resolves this vulnerability.Fixed in 7.0.0-1015.15 - Upgrade
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ubuntu/linux-nvidia-bosto a version that resolves this vulnerability.Fixed in 7.0.0-2022.23 - Upgrade
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ubuntu/linux-oem-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1015.15 - Upgrade
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ubuntu/linux-oracleto a version that resolves this vulnerability.Fixed in 7.0.0-1013.13 - Upgrade
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ubuntu/linux-realtimeto a version that resolves this vulnerability.Fixed in 7.0.0-38.38.1 - Upgrade
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ubuntu/linux-riscvto a version that resolves this vulnerability.Fixed in 7.0.0-38.38.1 - Configuration
Use DMA_BIDIRECTIONAL for both dma_map_single() and dma_unmap_single() in airoha_npu_send_msg() so dma_unmap_single() invalidates the CPU cache on non-coherent systems.
Linux kernel net: airoha NPU mailbox buffer DMA direction for mailbox buffer mapping and unmapping = DMA_BIDIRECTIONAL
Event History
Frequently Asked Questions
What is the severity of CVE-2026-68330?
CVE-2026-68330 has a severity score of 15, indicating a significant risk.
How do I fix CVE-2026-68330?
To fix CVE-2026-68330, update the Linux kernel to the latest version that includes the patch for this vulnerability.
What systems are affected by CVE-2026-68330?
CVE-2026-68330 affects systems running specific versions of the Linux kernel where the Airoha NPU driver is implemented.
What is the impact of CVE-2026-68330?
The impact of CVE-2026-68330 can lead to improper handling of DMA buffers, potentially causing data corruption.
When was CVE-2026-68330 published?
CVE-2026-68330 was published on August 10, 2026.