Linux Kernel Vulnerability in batman-adv Affects Counter Management

CVE-2026-52919

What is CVE-2026-52919?

In the Linux kernel, a vulnerability in batman-adv relates to improper management of the 'sending' atomic counter during shutdown operations. The function batadv_tp_sender_shutdown() decrements this counter unconditionally, which can lead to an underflow scenario, resulting in a negative value. When the sender logic interprets any non-zero value as 'still sending', this can cause the sender kthread to enter an infinite loop. As a consequence, a use-after-free issue may be triggered when the network interface is terminated while the zombie thread persists. The fix utilizes atomic_xchg() to accurately manage the counter’s transition from 1 to 0.

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