Linux Kernel Spinlock Deadlock Vulnerability in mac80211 Wi-Fi Module

A deadlock vulnerability has been identified in the Linux kernel's mac80211 Wi-Fi module, specifically within the ieee80211_tx_dequeue() function. The issue arises from a locking sequence that can be interrupted by asynchronous events, leading to a scenario where the same lock is acquired multiple times without being properly released. This can cause significant performance degradation by resetting the CPU and Wi-Fi device, or even result in a complete hang in single-CPU, single-core environments. The vulnerability has been addressed by modifying the locking mechanism to prevent such deadlocks.

Impact

Exploitation of this vulnerability can lead to a deadlock situation, causing the system to hang or requiring a costly reset of the CPU and Wi-Fi device.

Reproduction

The vulnerability can be reproduced by enabling ftrace testing, which increases the likelihood of asynchronous interrupts occurring during the critical section of the code where the spinlock is held. This can be done by configuring the Linux kernel to use ftrace and then triggering conditions that cause interrupts while the spinlock is engaged.

Remediation

Users can upgrade to the latest version of the Linux kernel where this vulnerability has been patched. The specific commit addressing this issue is available in the Linux kernel stable tree.