dax/fsdev: clear pgmap ops and owner on unbind

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.

Source published

17 Sep 2026 16:10:57 UTC

Source modified

19 Oct 2026 09:05:11 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

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