CVE-2025-40120: net: usb: asix: hold PM usage ref to avoid PM/MDIO + RTNL deadlock
In the Linux kernel, the following vulnerability has been resolved:
net: usb: asix: hold PM usage ref to avoid PM/MDIO + RTNL deadlock
Prevent USB runtime PM (autosuspend) for AX88772 in bind.
usbnet enables runtime PM (autosuspend) by default, so disabling it via the usbdriver flag is ineffective. On AX88772B, autosuspend shows no measurable power saving with current driver (no link partner, admin up/down). The ~0.453 W -> ~0.248 W drop on v6.1 comes from phylib powering the PHY off on admin-down, not from USB autosuspend.
The real hazard is that with runtime PM enabled, ndoopen() (under RTNL) may synchronously trigger autoresume (usbautopmgetinterface()) into asixresume() while the USB PM lock is held. Resume paths then invoke phylink/phylib and MDIO, which also expect RTNL, leading to possible deadlocks or PM lock vs MDIO wake issues.
To avoid this, keep the device runtime-PM active by taking a usage reference in ax88772bind() and dropping it in unbind(). A non-zero PM usage count blocks runtime suspend regardless of userspace policy (.../power/control - pmruntimeallow/forbid), making this approach robust against sysfs overrides.
Holding a runtime-PM usage ref does not affect system-wide suspend; system sleep/resume callbacks continue to run as before.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
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ubuntu/linux-gcp-6.8to a version that resolves this vulnerability.Fixed in 6.8.0-1052.55~22.04.1 - Upgrade
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ubuntu/linux-raspito a version that resolves this vulnerability.Fixed in 5.15.0-1097.100 - Upgrade
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ubuntu/linux-azure-fipsto a version that resolves this vulnerability.Fixed in 5.15.0-1109.118+fips1 - Upgrade
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ubuntu/linux-gcp-fipsto a version that resolves this vulnerability.Fixed in 5.15.0-1100.109+fips1 - Upgrade
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ubuntu/linuxto a version that resolves this vulnerability.Fixed in 6.8.0-106.106 - Upgrade
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ubuntu/linux-awsto a version that resolves this vulnerability.Fixed in 6.8.0-1050.53 - Upgrade
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ubuntu/linux-aws-6.17to a version that resolves this vulnerability.Fixed in 6.17.0-1007.7~24.04.1 - Upgrade
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ubuntu/linux-azureto a version that resolves this vulnerability.Fixed in 6.8.0-1051.57 - Upgrade
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ubuntu/linux-azure-fdeto a version that resolves this vulnerability.Fixed in 6.8.0-1058.65 - Upgrade
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ubuntu/linux-azure-nvidiato a version that resolves this vulnerability.Fixed in 6.8.0-1039.42 - Upgrade
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ubuntu/linux-gcpto a version that resolves this vulnerability.Fixed in 6.8.0-1052.55 - Upgrade
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ubuntu/linux-gcp-6.17to a version that resolves this vulnerability.Fixed in 6.17.0-1008.8~24.04.1 - Upgrade
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ubuntu/linux-gketo a version that resolves this vulnerability.Fixed in 6.8.0-1048.53 - Upgrade
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ubuntu/linux-gkeopto a version that resolves this vulnerability.Fixed in 6.8.0-1035.38 - Upgrade
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ubuntu/linux-ibmto a version that resolves this vulnerability.Fixed in 6.8.0-1049.49 - Upgrade
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ubuntu/linux-lowlatencyto a version that resolves this vulnerability.Fixed in 6.8.0-106.106.1 - Upgrade
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ubuntu/linux-nvidiato a version that resolves this vulnerability.Fixed in 6.8.0-1049.52 - Upgrade
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ubuntu/linux-nvidia-6.17to a version that resolves this vulnerability.Fixed in 6.17.0-1008.8 - Upgrade
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ubuntu/linux-nvidia-lowlatencyto a version that resolves this vulnerability.Fixed in 6.8.0-1049.52.1 - Upgrade
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ubuntu/linux-oracleto a version that resolves this vulnerability.Fixed in 6.8.0-1047.48 - Upgrade
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ubuntu/linux-oracle-6.17to a version that resolves this vulnerability.Fixed in 6.17.0-1007.7~24.04.1 - Upgrade
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ubuntu/linux-raspito a version that resolves this vulnerability.Fixed in 6.8.0-1050.54 - Upgrade
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ubuntu/linux-xilinxto a version that resolves this vulnerability.Fixed in 6.8.0-1028.29 - Upgrade
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ubuntu/linux-bluefieldto a version that resolves this vulnerability.Fixed in 6.8.0-1017.21 - Upgrade
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ubuntu/linux-raspi-realtimeto a version that resolves this vulnerability.Fixed in 6.8.0-2040.41 - Upgrade
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ubuntu/linux-realtimeto a version that resolves this vulnerability.Fixed in 6.8.1-1045.46 - Upgrade
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ubuntu/linux-realtime-6.17to a version that resolves this vulnerability.Fixed in 6.17.0-1006.7~24.04.1 - Upgrade
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ubuntu/linux-aws-fipsto a version that resolves this vulnerability.Fixed in 6.8.0-1050.53+fips1 - Upgrade
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ubuntu/linux-azure-fipsto a version that resolves this vulnerability.Fixed in 6.8.0-1052.58+fips1 - Upgrade
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ubuntu/linux-fipsto a version that resolves this vulnerability.Fixed in 6.8.0-106.106+fips1 - Upgrade
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ubuntu/linux-gcp-fipsto a version that resolves this vulnerability.Fixed in 6.8.0-1052.55+fips1 - Upgrade
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ubuntu/linuxto a version that resolves this vulnerability.Fixed in 6.17.0-14.14 - Upgrade
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ubuntu/linux-awsto a version that resolves this vulnerability.Fixed in 6.17.0-1007.7 - Upgrade
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ubuntu/linux-azureto a version that resolves this vulnerability.Fixed in 6.17.0-1008.8 - Upgrade
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ubuntu/linux-gcpto a version that resolves this vulnerability.Fixed in 6.17.0-1007.7 - Upgrade
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ubuntu/linux-oracleto a version that resolves this vulnerability.Fixed in 6.17.0-1007.7 - Upgrade
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ubuntu/linux-raspito a version that resolves this vulnerability.Fixed in 6.17.0-1008.8 - Upgrade
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ubuntu/linux-realtimeto a version that resolves this vulnerability.Fixed in 6.17.0-1006.7 - Upgrade
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ubuntu/linux-riscvto a version that resolves this vulnerability.Fixed in 6.17.0-14.14.1 - Compensating control
For AX88772* devices, keep runtime PM active by taking a runtime-PM usage reference in ax88772_bind() and dropping it in unbind(); this prevents USB runtime autosuspend and avoids the PM/MDIO + RTNL deadlock.
Event History
Frequently Asked Questions
What is the severity of CVE-2025-40120?
CVE-2025-40120 is classified as a medium severity vulnerability in the Linux kernel.
How do I fix CVE-2025-40120?
To fix CVE-2025-40120, update the Linux kernel to the latest stable version that includes the security patch.
What versions of the Linux kernel are affected by CVE-2025-40120?
CVE-2025-40120 affects Linux kernel versions from 6.1 onwards.
What does CVE-2025-40120 specifically address?
CVE-2025-40120 addresses a vulnerability in the USB network driver that could lead to a deadlock scenario.
What is the potential impact of CVE-2025-40120?
The potential impact of CVE-2025-40120 is that it may lead to system instability and unresponsive behavior due to a deadlock.