UBUNTU-CVE-2026-72454: Use After Free
In the Linux kernel, the following vulnerability has been resolved: i3c: mipi-i3c-hci: Fix race in i3chciaddrtodev() i3chciaddrtodev() walks bus->devs.i3c, which is protected by bus.lock (rwsem). However, it is invoked from the MIPI I3C HCI IRQ handler, which cannot take bus.lock. This allows concurrent device addition/removal in the I3C core to modify the list while it is being traversed, potentially leading to use-after-free or crashes. Remove the dependency on the bus device list and introduce a dedicated lookup table. Add an ibidevs[] array indexed by DAT entry, maintained under hci->lock. Update the array when IBIs are enabled or disabled, so that it always reflects the set of devices allowed to generate IBIs. Also update when IBIs are freed, to cover the corner case when an IBI is freed without first being disabled (e.g. oldedev in i3cmasteraddi3cdevlocked()). Move i3chciaddrtodev() into core.c, reimplement it using the new array, and add a lockdep assertion to enforce that hci->lock is held by callers. Demote a message in PIO and DMA IBI handling, from an error to a debug message, because there is a race window when the condition can arise normally.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
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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-nvidia-tegrato a version that resolves this vulnerability.Fixed in 6.8.0-1035.38 - 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 - Compensating control
Add a dedicated ibi_devs[] lookup array indexed by DAT entry, protected by hci->lock, and update it when IBIs are enabled, disabled, or freed so it reflects devices allowed to generate IBIs, including IBIs freed without first being disabled.
- Compensating control
Move i3c_hci_addr_to_dev() into core.c, reimplement it using the ibi_devs[] array instead of bus->devs.i3c, and add a lockdep assertion requiring hci->lock to be held by callers.
- Compensating control
Demote the message for the race condition in PIO and DMA IBI handling from error level to debug level because the condition can arise normally.
Event History
Frequently Asked Questions
Which systems are most likely to be exposed?
The affected Ubuntu kernel packages are linux, linux-realtime, linux-azure, linux-gcp, linux-azure-fde, linux-gke, linux-riscv, and linux-gkeop. The vulnerable path involves the MIPI I3C HCI driver and handling of in-band interrupts (IBIs), so systems using that hardware and functionality are the relevant exposure set.
What does exploitation require?
The supplied vector indicates local access with low attack complexity and low privileges, with no user interaction required. Exploitation depends on racing I3C device-list changes, such as device addition or removal, against processing in the I3C HCI IRQ handler.
What security impact can result from the race?
Concurrent modification of the I3C device list while it is traversed can cause a use-after-free or kernel crash. The provided severity vector rates confidentiality, integrity, and availability impact as high.