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CVE-2025-21781 – Linux batman-adv Interface Removal Panic

The following table lists the changes that have been made to the
CVE-2025-21781 vulnerability over time.

Vulnerability history details can be useful for understanding the evolution
of a vulnerability, and for identifying the most recent changes that may
impact the vulnerability’s severity, exploitability, or other characteristics.

  • New CVE Received
    by 416baaa9-dc9f-4396-8d5f-8c081fb06d67

    Feb. 27, 2025

    Action Type Old Value New Value
    Added Description In the Linux kernel, the following vulnerability has been resolved:

    batman-adv: fix panic during interface removal

    Reference counting is used to ensure that
    batadv_hardif_neigh_node and batadv_hard_iface
    are not freed before/during
    batadv_v_elp_throughput_metric_update work is
    finished.

    But there isn’t a guarantee that the hard if will
    remain associated with a soft interface up until
    the work is finished.

    This fixes a crash triggered by reboot that looks
    like this:

    Call trace:
    batadv_v_mesh_free+0xd0/0x4dc [batman_adv]
    batadv_v_elp_throughput_metric_update+0x1c/0xa4
    process_one_work+0x178/0x398
    worker_thread+0x2e8/0x4d0
    kthread+0xd8/0xdc
    ret_from_fork+0x10/0x20

    (the batadv_v_mesh_free call is misleading,
    and does not actually happen)

    I was able to make the issue happen more reliably
    by changing hardif_neigh->bat_v.metric_work work
    to be delayed work. This allowed me to track down
    and confirm the fix.

    [[email protected]: prevent entering batadv_v_elp_get_throughput without
    soft_iface]
    Added Reference https://git.kernel.org/stable/c/072b2787321903287a126c148e8db87dd7ef96fe
    Added Reference https://git.kernel.org/stable/c/2c3fb7df4cc6d043f70d4a8a10f8b915bbfb75e7
    Added Reference https://git.kernel.org/stable/c/522b1596ea19e327853804da2de60aeb9c5d6f42
    Added Reference https://git.kernel.org/stable/c/7eb5dd201695645af071592a50026eb780081a72
    Added Reference https://git.kernel.org/stable/c/ccb7276a6d26d6f8416e315b43b45e15ee7f29e2
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