UBUNTU-CVE-2025-68822: Use After Free
In the Linux kernel, the following vulnerability has been resolved: Input: alps - fix use-after-free bugs caused by dev3registerwork The dev3registerwork delayed work item is initialized within alpsreconnect() and scheduled upon receipt of the first bare PS/2 packet from an external PS/2 device connected to the ALPS touchpad. During device detachment, the original implementation calls flushworkqueue() in psmousedisconnect() to ensure completion of dev3registerwork. However, the flushworkqueue() in psmousedisconnect() only blocks and waits for work items that were already queued to the workqueue prior to its invocation. Any work items submitted after flushworkqueue() is called are not included in the set of tasks that the flush operation awaits. This means that after flushworkqueue() has finished executing, the dev3registerwork could still be scheduled. Although the psmouse state is set to PSMOUSECMDMODE in psmousedisconnect(), the scheduling of dev3registerwork remains unaffected. The race condition can occur as follows: CPU 0 (cleanup path) | CPU 1 (delayed work) psmousedisconnect() | psmousesetstate() | flushworkqueue() | alpsreportbareps2packet() alpsdisconnect() | psmousequeuework() kfree(priv); // FREE | alpsregisterbareps2mouse() | priv = containerof(work...); // USE | priv->dev3 // USE Add disabledelayedworksync() in alpsdisconnect() to ensure that dev3registerwork is properly canceled and prevented from executing after the alpsdata structure has been deallocated. This bug is identified by static analysis.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
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ubuntu/linux-aws-6.17to a version that resolves this vulnerability.Fixed in 6.17.0-1012.12~24.04.1 - Upgrade
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ubuntu/linux-azure-6.17to a version that resolves this vulnerability.Fixed in 6.17.0-1013.13~24.04.1 - Upgrade
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ubuntu/linux-gcp-6.17to a version that resolves this vulnerability.Fixed in 6.17.0-1012.12~24.04.1 - Upgrade
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ubuntu/linux-hwe-6.17to a version that resolves this vulnerability.Fixed in 6.17.0-22.22~24.04.1 - Upgrade
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ubuntu/linux-nvidia-6.17to a version that resolves this vulnerability.Fixed in 6.17.0-1018.18 - 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-oem-6.17to a version that resolves this vulnerability.Fixed in 6.17.0-1020.20 - Upgrade
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ubuntu/linux-oracle-6.17to a version that resolves this vulnerability.Fixed in 6.17.0-1011.11~24.04.1 - Upgrade
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ubuntu/linux-riscv-6.17to a version that resolves this vulnerability.Fixed in 6.17.0-22.22.1~24.04.1 - Upgrade
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ubuntu/linux-realtime-6.17to a version that resolves this vulnerability.Fixed in 6.17.0-1010.11~24.04.1 - Upgrade
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ubuntu/linuxto a version that resolves this vulnerability.Fixed in 6.17.0-22.22 - Upgrade
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ubuntu/linux-awsto a version that resolves this vulnerability.Fixed in 6.17.0-1012.12 - Upgrade
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ubuntu/linux-azureto a version that resolves this vulnerability.Fixed in 6.17.0-1013.13 - Upgrade
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ubuntu/linux-gcpto a version that resolves this vulnerability.Fixed in 6.17.0-1012.12 - Upgrade
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ubuntu/linux-oracleto a version that resolves this vulnerability.Fixed in 6.17.0-1011.11 - Upgrade
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ubuntu/linux-raspito a version that resolves this vulnerability.Fixed in 6.17.0-1013.13 - Upgrade
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ubuntu/linux-realtimeto a version that resolves this vulnerability.Fixed in 6.17.0-1010.11 - Upgrade
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ubuntu/linux-riscvto a version that resolves this vulnerability.Fixed in 6.17.0-22.22.1 - Configuration
Add disable_delayed_work_sync() in alps_disconnect() to cancel dev3_register_work and prevent it from executing after the alps_data structure is deallocated.
Linux kernel Input: alps disable_delayed_work_sync() = called in alps_disconnect()
Event History
Frequently Asked Questions
Which systems are exposed to this race condition?
The issue applies to the listed Ubuntu kernel packages, including linux, linux-aws, linux-azure, linux-gcp, and their FIPS variants, when an ALPS touchpad has an external PS/2 device connected to it.
What condition triggers the use-after-free risk?
The race occurs during device detachment if the ALPS delayed registration work is scheduled after psmouse_disconnect() has completed its workqueue flush. Receipt of the first bare PS/2 packet from the connected external device can schedule that delayed work.