UBUNTU-CVE-2026-74617: Critical severity ubuntu/linux-hwe-edge vulnerability
In the Linux kernel, the following vulnerability has been resolved: dibs: initialise dibs->lock in dibsdevalloc() dibs->lock is initialised by dibsdevadd(), but a dibs device can already take interrupts before that call: ismprobe() runs ismdevinit(), and hence requestirq(), before it calls dibsdevadd(). No client can have registered a dmb at that point, so no dmb interrupt can occur, but a GID event interrupt can, and ismhandleirq() takes dibs->lock unconditionally on entry, before it inspects anything else. Initialise the lock in dibsdevalloc() instead, so that it is valid as soon as a driver can publish the device to its interrupt handler.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
ubuntu/linux-hwe-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-42.42~24.04.1 - Upgrade
Upgrade
ubuntu/linux-riscv-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-42.42.1~24.04.1 - Upgrade
Upgrade
ubuntu/linuxto a version that resolves this vulnerability.Fixed in 7.0.0-42.42 - Upgrade
Upgrade
ubuntu/linux-awsto a version that resolves this vulnerability.Fixed in 7.0.0-1016.17 - Upgrade
Upgrade
ubuntu/linux-gcpto a version that resolves this vulnerability.Fixed in 7.0.0-1016.18 - Upgrade
Upgrade
ubuntu/linux-ibmto a version that resolves this vulnerability.Fixed in 7.0.0-1017.17 - Upgrade
Upgrade
ubuntu/linux-oem-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1017.17 - Upgrade
Upgrade
ubuntu/linux-oracleto a version that resolves this vulnerability.Fixed in 7.0.0-1015.16 - Upgrade
Upgrade
ubuntu/linux-riscvto a version that resolves this vulnerability.Fixed in 7.0.0-42.42.1
Event History
Frequently Asked Questions
What condition can trigger the issue during device initialization?
A dibs device can receive interrupts after request_irq() is registered in ism_probe() but before dibs_dev_add() initializes dibs->lock. A GID event interrupt in that window causes ism_handle_irq() to take an uninitialized lock.
Does exploitation require a registered DMB client or a DMB interrupt?
No. Although no client can have registered a DMB at that stage, a GID event interrupt can still occur and reach the handler.
Which Ubuntu kernel packages are identified as affected?
The listed packages are ubuntu/linux-riscv, ubuntu/linux-realtime, ubuntu/linux-hwe-edge, ubuntu/linux-azure, ubuntu/linux-gcp, ubuntu/linux-azure-fde, ubuntu/linux-gke, and ubuntu/linux-aws-5.0.