UBUNTU-CVE-2026-80778: Medium severity ubuntu/linux-hwe-edge vulnerability
In the Linux kernel, the following vulnerability has been resolved: futex/pi: Reject cross-mm private futex owners A private futex key borrows the waiter's mm without taking an mmusers reference. Nevertheless, attachtopiowner() currently accepts an owner from a different address space and copies the private key into the owner's PI state. When that owner exits, exitpistatelist() uses the saved key to find the hash bucket and acquires a reference to the waiter's private hash. If the last user of the waiter's mm exits concurrently, futexhashfree() frees the hash while the owner still uses its bucket and reference. Prevent this by validating in attachtopiowner() that, for private futexes, the owner mm and waiter mm are the same. Perform the check with the owner's pilock held and after validating owner::futex::state to serialize against a concurrent PI-state exit cleanup. [ tglx: Amended comment ]
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
Which Ubuntu kernel packages are identified as affected?
The affected software list includes 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. The provided data does not identify affected or fixed package versions.
What conditions are required to trigger the issue?
The issue involves a private priority-inheritance futex whose waiter and owner belong to different address spaces. Exploitation also depends on concurrent process exit activity: the waiter's memory-management context can be torn down while the owner still uses the saved private futex hash bucket.