CVE-2026-80554: s390/vfio_ccw: Limit the number of channel program segments
In the Linux kernel, the following vulnerability has been resolved:
s390/vfioccw: Limit the number of channel program segments
The processing of channel programs, and the CCWs within them, is done recursively. As such, there is an arbitrary (but not architectural) limit to the number of CCWs that can exist in a single channel program.
The vfio-ccw logic breaks these channel programs into segments whenever it encounters a Transfer-In-Channel (TIC) CCW, and the combined number of segments count towards the global limit. Impose an equivalent limit to the number of segments until such logic can be made non-recursive.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 6.6.157.1-1 - Upgrade
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debian/linuxto a version that resolves this vulnerability.Fixed in 6.12.105-1 - Upgrade
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debian/linuxto a version that resolves this vulnerability.Fixed in 7.1.10-1 - Upgrade
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debian/linux-6.12to a version that resolves this vulnerability.Fixed in 6.12.107-1~deb12u1 - Upgrade
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linux/Kernelto a version that resolves this vulnerability.Fixed in 6.1.191 - Upgrade
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linux/Kernelto a version that resolves this vulnerability.Fixed in 6.6.153 - Upgrade
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linux/Kernelto a version that resolves this vulnerability.Fixed in 6.12.105 - Upgrade
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linux/Kernelto a version that resolves this vulnerability.Fixed in 6.18.46 - Upgrade
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linux/Kernelto a version that resolves this vulnerability.Fixed in 7.1.10 - Upgrade
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debian/linuxto a version that resolves this vulnerability.Fixed in 6.12.107-1Fixed 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-nvidia-tegrato a version that resolves this vulnerability.Fixed in 6.8.0-1036.39 - 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
For Linux s390/vfio_ccw, impose a limit on the number of channel program segments equivalent to the existing limit on CCWs in a single channel program, until processing can be made non-recursive.
Event History
Frequently Asked Questions
Which systems are in scope?
The issue is in the Linux kernel's s390 vfio-ccw logic. The provided information does not identify affected kernel versions or configuration prerequisites.
What kind of channel program is relevant to this issue?
Channel programs containing Transfer-In-Channel (TIC) CCWs are split into segments by vfio-ccw. The combined segment count contributes to the global limit while the channel-program processing remains recursive.