CVE-2025-40120

net: usb: asix: hold PM usage ref to avoid PM/MDIO + RTNL deadlock

State: Published
Severity: Not scored
Published: Nov 12, 2025
Updated: May 11, 2026
Reserved: Apr 16, 2025

Description

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 usb_driver 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, ndo_open() (under RTNL) may synchronously trigger autoresume (usb_autopm_get_interface()) into asix_resume() 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 ax88772_bind() and dropping it in unbind(). A non-zero PM usage count blocks runtime suspend regardless of userspace policy (.../power/control - pm_runtime_allow/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.

Scores

The record has no CVSS score.

Weaknesses

The record names no weakness.

Affected Products

Product	Versions
LinuxLinux	4a2c7217cd5a87e85ceb761e307b030fe6db4805 to before 71a0ba7fdaf8d035426912a4ed7bf1738a81010cAffected 4a2c7217cd5a87e85ceb761e307b030fe6db4805 to before 3e96cd27ff1a004d84908c1b6cc68ac60913874eAffected 4a2c7217cd5a87e85ceb761e307b030fe6db4805 to before 724a9db84188f80ef60b1f21cc7b4e9c84e0cb64Affected 4a2c7217cd5a87e85ceb761e307b030fe6db4805 to before 1534517300e12f2930b6ff477b8820ff658afd11Affected 4a2c7217cd5a87e85ceb761e307b030fe6db4805 to before 9d8bcaf6fae1bd82bc27ec09a2694497e6f6c4b4Affected 4a2c7217cd5a87e85ceb761e307b030fe6db4805 to before 3d3c4cd5c62f24bb3cb4511b7a95df707635e00aAffected
LinuxLinux	5.14Affected before 5.14Not affected 5.15.195 through 5.15.Not affected 6.1.156 through 6.1.Not affected 6.6.112 through 6.6.Not affected 6.12.53 through 6.12.Not affected 6.17.3 through 6.17.*Not affected 6.18 and laterNot affected

Product

Versions

LinuxLinux

4a2c7217cd5a87e85ceb761e307b030fe6db4805 to before 71a0ba7fdaf8d035426912a4ed7bf1738a81010cAffected
4a2c7217cd5a87e85ceb761e307b030fe6db4805 to before 3e96cd27ff1a004d84908c1b6cc68ac60913874eAffected
4a2c7217cd5a87e85ceb761e307b030fe6db4805 to before 724a9db84188f80ef60b1f21cc7b4e9c84e0cb64Affected
4a2c7217cd5a87e85ceb761e307b030fe6db4805 to before 1534517300e12f2930b6ff477b8820ff658afd11Affected
4a2c7217cd5a87e85ceb761e307b030fe6db4805 to before 9d8bcaf6fae1bd82bc27ec09a2694497e6f6c4b4Affected
4a2c7217cd5a87e85ceb761e307b030fe6db4805 to before 3d3c4cd5c62f24bb3cb4511b7a95df707635e00aAffected

LinuxLinux

5.14Affected
before 5.14Not affected
5.15.195 through 5.15.*Not affected
6.1.156 through 6.1.*Not affected
6.6.112 through 6.6.*Not affected
6.12.53 through 6.12.*Not affected
6.17.3 through 6.17.*Not affected
6.18 and laterNot affected

References

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