CVE-2025-21781 Affecting linux-6.1 package, versions <6.1.129-1~deb11u1


Severity

Recommended
low

Based on default assessment until relevant scores are available.

Threat Intelligence

EPSS
0.08% (24th percentile)

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  • Snyk IDSNYK-DEBIAN11-LINUX61-9576016
  • published1 Apr 2025
  • disclosed27 Feb 2025

Introduced: 27 Feb 2025

CVE-2025-21781  (opens in a new tab)

How to fix?

Upgrade Debian:11 linux-6.1 to version 6.1.129-1~deb11u1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream linux-6.1 package and not the linux-6.1 package as distributed by Debian. See How to fix? for Debian:11 relevant fixed versions and status.

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.

[sven@narfation.org: prevent entering batadv_v_elp_get_throughput without soft_iface]

CVSS Base Scores

version 3.1