UBUNTU-CVE-2026-97411: Medium severity ubuntu/linux vulnerability
In the Linux kernel, the following vulnerability has been resolved: net: ibm: emac: mal: fix potential system hang in malremove() napidisable() is not idempotent and calling it on an already-disabled or unenabled NAPI context will cause the kernel to spin indefinitely waiting for the NAPISTATESCHED bit to clear. In malremove(), napidisable() is called unconditionally. If no MACs were registered, NAPI was never enabled. Also, if they were registered but subsequently unregistered, NAPI was already disabled in malunregistercommac(). In either case, calling napidisable() causes the kernel to hang upon module removal. Fix this by only calling napidisable() in malremove() if the commac list is not empty (which implies NAPI is enabled).
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
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ubuntu/linux-aws-5.15to a version that resolves this vulnerability.Fixed in 5.15.0-1119.126~20.04.1 - Upgrade
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ubuntu/linux-riscvto a version that resolves this vulnerability.Fixed in 7.0.0-42.42.1 - Configuration
Change mal_remove() so napi_disable() is called only when the commac list is not empty, which implies NAPI is enabled; do not call it when no MACs were registered or after they were unregistered.
Linux kernel net: ibm: emac: mal napi_disable() in mal_remove() = Call only if the commac list is not empty
Event History
Frequently Asked Questions
When can this issue cause a system hang?
The hang occurs during removal of the IBM EMAC MAL module when napi_disable() is called on a NAPI context that was never enabled or was already disabled. This can happen when no MACs were registered, or when registered MACs were later unregistered before module removal.
What action triggers the vulnerable path?
Removing the affected module triggers mal_remove(), which unconditionally calls napi_disable() in the vulnerable implementation. The kernel can then spin indefinitely waiting for the NAPI_STATE_SCHED bit to clear.
How does the fix prevent the hang?
The fix calls napi_disable() in mal_remove() only when the commac list is not empty. A non-empty commac list implies that NAPI is enabled, avoiding a disable operation on an unenabled or already-disabled context.