CVE-2026-63973: net: mana: Add NULL guards in teardown path to prevent panic on attach failure
In the Linux kernel, the following vulnerability has been resolved:
net: mana: Add NULL guards in teardown path to prevent panic on attach failure
When queue allocation fails partway through, the error cleanup frees and NULLs apc->txqp and apc->rxqs. Multiple teardown paths such as manaremove(), manachangemtu() recovery, and internal error handling in manaallocqueues() can subsequently call into functions that dereference these pointers without NULL checks:
- manachnsetxdp() dereferences apc->rxqs[0], causing a NULL pointer dereference panic (CR2: 0000000000000000 at manachnsetxdp+0x26). - manadestroyvport() iterates apc->rxqs without a NULL check. - manafencerqs() iterates apc->rxqs without a NULL check. - manadeallocqueues() iterates apc->txqp without a NULL check.
Add NULL guards for apc->rxqs in manafencerqs(), manadestroyvport(), and before the manachnsetxdp() call. Add a NULL guard for apc->txqp in manadeallocqueues() to skip TX queue draining when TX queues were never allocated or already freed.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
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ubuntu/linuxto a version that resolves this vulnerability.Fixed in 7.0.0-28.28 - Upgrade
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ubuntu/linux-riscvto a version that resolves this vulnerability.Fixed in 7.0.0-28.28.1 - Compensating control
In the Linux kernel net: mana teardown and recovery paths, add NULL guards for apc->rxqs in mana_fence_rqs() and mana_destroy_vport(), guard apc->rxqs before the mana_chn_setxdp() call, and guard apc->tx_qp in mana_dealloc_queues() so TX queue draining is skipped when queues were never allocated or were already freed.
Event History
Frequently Asked Questions
What conditions are required to trigger the panic?
Queue allocation must fail partway through attachment, leaving the transmit queue pointer or receive-queue array freed and set to NULL. A later teardown, MTU-change recovery, or internal queue-allocation error-handling path must then operate on those unallocated or already-freed queues.
What is the practical impact?
The affected paths can dereference a NULL pointer and panic the kernel. The CVSS vector indicates local access with low privileges is required, and the impact is limited to availability.
Which operations may encounter the unsafe cleanup path?
The described paths include device removal, recovery during an MTU change, and internal error handling in queue allocation. The vulnerable operations include XDP setup, vport destruction, receive-queue fencing, and transmit-queue deallocation when their corresponding queue structures are NULL.
What mitigation is available if the fix cannot be applied immediately?
The provided information does not identify a configuration workaround. Reducing opportunities for unprivileged local users to initiate or influence affected network-device operations may reduce exposure, but the described remediation is to add NULL guards in the teardown paths.