CVE-2025-21781 — batman-adv: fix panic during interface removal

Affected: Linux

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]

USN-7510-1 — linux, linux-gkeop, linux-ibm, linux-ibm-5.15, linux-intel-iotg, linux-kvm, linux-lowlatency, linux-lowlatency-hwe-5.15…

Affected: Ubuntu:20.04:LTS: linux-ibm-5.15, Ubuntu:20.04:LTS: linux-lowlatency-hwe-5.15, Ubuntu:20.04:LTS: linux-oracle-5.15, Ubuntu:22.04:LTS: linux, Ubuntu:22.04:LTS: linux-gkeop, Ubuntu:22.04:LTS: linux-ibm, Ubuntu:22.04:LTS: linux-intel-iotg, Ubuntu:22.04:LTS: linux-kvm, Ubuntu:22.04:LTS: linux-lowlatency, Ubuntu:22.04:LTS: linux-nvidia and 1 more

Several security issues were discovered in the Linux kernel. An attacker could possibly use these to compromise the system. This update corrects flaws in the following subsystems: - ARM64 architecture; - PowerPC architecture; - x86 architecture; - Block layer subsystem; - Network block device driver; - Bus devices; - Character device driver; - TPM device driver; - Clock framework and drivers; - GPIO subsystem; - GPU drivers; - HID subsystem; - I2C subsystem; - InfiniBand drivers; - Media drivers; - NVIDIA Tegra memory controller driver; - Network drivers; - PCI subsystem; - PPS (Pulse Per Second) driver; - PTP clock framework; - RapidIO drivers; - Real Time Clock drivers; - SLIMbus drivers; - QCOM SoC drivers; - Trusted Execution Environment drivers; - TTY drivers; - USB DSL drivers; - USB Device Class drivers; - USB core drivers; - USB Gadget drivers; - USB Host Controller drivers; - Renesas USBHS Controller drivers; - ACRN Hypervisor Service Module driver; - File systems infrastructure; - BTRFS file system; - F2FS file system; - Network file system (NFS) server daemon; - NILFS2 file system; - Overlay file system; - SMB network file system; - UBI file system; - KVM subsystem; - L3 Master device support module; - Process Accounting mechanism; - Padata parallel execution mechanism; - printk logging mechanism; - Scheduler infrastructure; - Timer subsystem; - Tracing infrastructure…

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CVE-2025-21781 — batman-adv: fix panic during interface removal

USN-7510-1 — linux, linux-gkeop, linux-ibm, linux-ibm-5.15, linux-intel-iotg, linux-kvm, linux-lowlatency, linux-lowlatency-hwe-5.15…