CVE-2026-98619
Received Received - Intake

Race Condition in Linux Kernel ethtool Self-Test

Publication date: 2026-10-18

Last updated on: 2026-10-18

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: net: ethtool: keep rtnl_lock for the ioctl self test An offline self test that brings the interface down and back up with netif_close() / netif_open() requires rtnl_lock for both. Since the ethtool IOCTL path became rtnl-optional for ops-locked drivers, the ETHTOOL_TEST ioctl runs holding only the netdev instance lock, so on an ops-locked driver the self test now tears the device down without rtnl_lock. With lockdep this reproduces deterministically on every offline self test on such a driver; note the sole lock held is the instance lock, not rtnl: WARNING: suspicious RCU usage net/core/netpoll.c:207 suspicious rcu_dereference_protected() usage! 1 lock held by ethtool/107: #0: (&dev->lock){+.+.}, at: dev_ethtool Call Trace: netpoll_poll_disable __dev_close_many netif_close_many netif_close fbnic_self_test dev_ethtool_locked dev_ethtool dev_ioctl sock_ioctl __x64_sys_ioctl Without lockdep the same condition trips ASSERT_RTNL() in __dev_close_many() / __dev_open(); that check only samples the global rtnl state, so it can be masked by a concurrent rtnl holder, but the device is still being reconfigured without the lock it requires. The ethtool self_test is a legacy ioctl-only command, so an ETHTOOL_TEST case is only needed on the ioctl path. Add an opt-in bit for drivers whose self test needs rtnl_lock and set it on the ops-locked drivers whose offline self test tears the interface down and up: - fbnic (ops-locked via queue_mgmt_ops): fbnic_self_test() offline path uses netif_close() / netif_open(). - bnxt (ops-locked via queue_mgmt_ops): bnxt_self_test() offline path goes through bnxt_close_nic() / bnxt_half_open_nic() / bnxt_half_close_nic() / bnxt_open_nic(), which close and reopen the device.

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Meta Information

Published
2026-10-18
Last Modified
2026-10-18
Generated
2026-10-18
AI Q&A
2026-10-18
EPSS Evaluated
N/A
NVD
CVE-2026-98619
EUVD
EUVD-2026-103664

Affected Vendors & Products

Showing 3 associated CPEs
Vendor Product Version / Range
Linux Linux f994752b11273ded7ec6b49ae5c1d319eef21743
Linux Linux f994752b11273ded7ec6b49ae5c1d319eef21743
Linux Linux 7.2

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Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability in the Linux kernel involves the ethtool self-test feature. When performing an offline self-test that temporarily brings down and restarts a network interface, the operation requires the rtnl_lock (routing netlink lock) to safely reconfigure the device. However, the ethtool IOCTL path became rtnl-optional for certain drivers, causing the self-test to proceed without this critical lock. This can lead to race conditions and improper device state management.

Detection Guidance

This vulnerability is specific to the Linux kernel's ethtool self-test functionality and requires kernel-level detection. It manifests as a lockdep warning or ASSERT_RTNL() failure during offline self-tests on ops-locked drivers like fbnic or bnxt. No direct network or system commands detect this; kernel logs showing 'suspicious RCU usage' or 'ASSERT_RTNL()' indicate the issue.

Impact Analysis

This vulnerability may cause network interface instability or crashes during ethtool self-tests on affected systems. It could lead to unexpected behavior, data corruption, or denial of service if the device is improperly reconfigured without proper synchronization. Systems using ops-locked drivers like fbnic or bnxt are particularly affected.

Mitigation Strategies

Apply the kernel patch that adds the ETHTOOL_TEST opt-in bit for drivers requiring rtnl_lock during self-tests. Update affected drivers (fbnic, bnxt) to set this bit. Monitor kernel logs for lockdep warnings or ASSERT_RTNL() failures as indicators of the issue.

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