CVE-2026-98344: dmaengine: Fix device kref underflow in dma_chan_put()
dmaengine: Fix device kref underflow in dmachanput()
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
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Fixed in 6.6.158.1-1 - Upgrade
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debian/linuxto a version that resolves this vulnerability.Fixed in 6.1.190-1Fixed in 6.12.115-2Fixed in 7.2.12-1Fixed in 7.2.15-1 - Upgrade
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debian/linux-6.12to a version that resolves this vulnerability.Fixed in 6.12.113-1~deb12u1 - Upgrade
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ubuntu/linux-hwe-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-42.42~24.04.1 - Upgrade
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ubuntu/linux-riscv-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-42.42.1~24.04.1 - Upgrade
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ubuntu/linuxto a version that resolves this vulnerability.Fixed in 7.0.0-42.42 - Upgrade
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ubuntu/linux-awsto a version that resolves this vulnerability.Fixed in 7.0.0-1016.17 - Upgrade
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ubuntu/linux-gcpto a version that resolves this vulnerability.Fixed in 7.0.0-1016.18 - Upgrade
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ubuntu/linux-ibmto a version that resolves this vulnerability.Fixed in 7.0.0-1017.17 - Upgrade
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ubuntu/linux-oem-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1017.17 - Upgrade
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ubuntu/linux-oracleto a version that resolves this vulnerability.Fixed in 7.0.0-1015.16 - Upgrade
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ubuntu/linux-riscvto a version that resolves this vulnerability.Fixed in 7.0.0-42.42.1 - Compensating control
Modify the Linux kernel dmaengine dma_chan_put() logic to drop chan->device->ref only on the last put, matching the single slow-path reference acquired by dma_chan_get().
Event History
Frequently Asked Questions
What conditions are required for this issue to occur?
The affected DMA provider must be non-private and have a persistent client keeping chan->client_count greater than zero. A separate client must repeatedly cycle dmaengine_get() and dmaengine_put() on the channel.
What is the observable impact if the reference count reaches zero?
A later dma_find_channel() call returns NULL even though the DMA provider module remains loaded. This can prevent the channel from being found or used by subsequent clients.
Are systems using only a single DMA client exposed to this reference-count underflow?
The described failure requires both a persistent client and another client performing get/put cycles. The data does not describe the issue occurring with only one client.
What change resolves the issue?
The fix drops the device reference only on the last dma_chan_put(), matching the single device-reference acquisition on the slow path in dma_chan_get().