Linux Kernel CVE-2025-40347

In the Linux kernel, the following vulnerability has been resolved:

net: enetc: fix the deadlock of enetc_mdio_lock

After applying the workaround for err050089, the LS1028A platform experiences RCU stalls on RT kernel. This issue is caused by the recursive acquisition of the read lock enetc_mdio_lock. Here list some of the call stacks identified under the enetc_poll path that may lead to a deadlock:

enetc_poll -> enetc_lock_mdio -> enetc_clean_rx_ring OR napi_complete_done -> napi_gro_receive -> enetc_start_xmit -> enetc_lock_mdio -> enetc_map_tx_buffs -> enetc_unlock_mdio -> enetc_unlock_mdio

After enetc_poll acquires the read lock, a higher-priority writer attempts to acquire the lock, causing preemption. The writer detects that a read lock is already held and is scheduled out. However, readers under enetc_poll cannot acquire the read lock again because a writer is already waiting, leading to a thread hang.

Currently, the deadlock is avoided by adjusting enetc_lock_mdio to prevent recursive lock acquisition.

The Linux kernel's Freescale/NXP enetc Ethernet driver as used on the NXP LS1028A (Layerscape) platform, specifically affecting PREEMPT_RT (real-time) kernel configurations where the err050089 MDIO workaround is applied. Exact vulnerable version ranges were not enumerated in the feed (no CPE strings and no NVD-assigned version data were provided); affected/fixed branches must be derived from the stable-tree commits. Fix commits are published at git.kernel.org/stable/c/1f92f5bd057a4fad9dab6af17963cdd21e5da6ed, /2781ca82ce8cad263d80b617addb727e6a84c9e5, /2e55a49dc3b2a6b23329e4fbbd8a5feb20e220aa, /50bd33f6b3922a6b760aa30d409cae891cec8fb5, and /a649161526736f48bcc592e3a412e5bcd7dd9e24, indicating backports across multiple stable series.