Linux Kernel Spinlock Recursion Vulnerability in MediaTek MT8365 Ethernet Driver

A vulnerability has been identified in the Linux kernel's MediaTek MT8365 Ethernet driver, specifically in the mtk_star_emac component. This vulnerability arises from improper handling of spinlocks, which can lead to recursion issues during receive and transmit polling. The problem occurs when DMA interrupts are re-enabled, potentially causing a deadlock situation. The vulnerability has been addressed by modifying the driver to use spin_lock_irqsave and spin_unlock_irqrestore, replacing the previous spin_lock and spin_unlock methods. This change prevents the recursion from occurring by properly managing the interrupt handling and ensuring that the spinlock is released correctly after use.

Impact

Exploitation of this vulnerability can lead to spinlock recursion, causing a deadlock situation where the system becomes unresponsive. This can disrupt normal operations and potentially cause performance issues or crashes.

Reproduction

The vulnerability can be reproduced by enabling DMA interrupts in the mtk_star_emac driver while using the standard spinlock functions. This will trigger a recursion issue on the specified CPU, as the interrupts can interfere with the polling process, leading to a deadlock.

Remediation

The vulnerability has been fixed in the official Linux kernel repository. Users should upgrade to the latest version of the kernel where this fix is applied.