Linux Kernel up to 7.2.5 dax/fsdev device.c fsdev_dax_probe use after free

Summaryinfo

A vulnerability was found in Linux Kernel up to 7.2.5 and classified as very critical. This issue affects the function fsdev_dax_probe of the file device.c of the component dax/fsdev. Such manipulation leads to use after free. This vulnerability is referenced as CVE-2026-93075. The attack can only be performed from a local environment. No exploit is available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as very critical, has been found in Linux Kernel up to 7.2.5. Affected by this issue is the function fsdev_dax_probe of the file device.c of the component dax/fsdev. The manipulation with an unknown input leads to a use after free vulnerability. Using CWE to declare the problem leads to CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. Impacted is confidentiality, integrity, and availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: dax/fsdev: clear pgmap ops and owner on unbind fsdev_dax_probe() sets pgmap->ops = &fsdev_pagemap_ops and pgmap->owner = dev_dax, but nothing ever clears them. For a dynamic device the pgmap is devm-allocated and freed on unbind, so this is harmless. For a static device the pgmap is the shared, long-lived one owned by the dax bus (kill_dev_dax() only NULLs dev_dax->pgmap for the non-static case), and device.c's probe sets only pgmap->type, never clearing ops/owner. So after fsdev unbinds a static device the stale fsdev_pagemap_ops survives on the shared pgmap. If the device is then rebound to device_dax (MEMORY_DEVICE_GENERIC, which installs no ->memory_failure), or the fsdev_dax module is unloaded, a subsequent memory_failure on that pgmap dispatches through the stale -- and possibly freed -- handler. Register a devm action that clears pgmap->ops and pgmap->owner on unbind, symmetric with setting them at probe, so the pgmap carries no fsdev state once fsdev is detached.

The advisory is shared for download at git.kernel.org. This vulnerability is handled as CVE-2026-93075 since 09/17/2026. The exploitation is known to be easy. The attack needs to be approached locally. The exploitation requires an enhanced level of successful authentication. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 09/17/2026).

Upgrading to version 7.2.6 or 7.3-rc1 eliminates this vulnerability. Applying the patch 9b0f91dc9147a8601cec3d4d83cf13c6aaf71b27/f48884ac31b6bfc99f36b3f207b8c0cbe5d54bd7 is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 7.2.0
• 7.2.1
• 7.2.2
• 7.2.3
• 7.2.4
• 7.2.5

License

• open-source

Website

• Vendor: https://www.kernel.org/

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