# CVE-2026-64472: vfio/mlx5: Fix racy bitfields and tighten struct layout

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2026-07-25 · Updated: 2026-08-17

## Affected

- Linux: version range not reported
- Linux: 5.19

## Description

In the Linux kernel, the following vulnerability has been resolved: vfio/mlx5: Fix racy bitfields and tighten struct layout Bitfield operations are not atomic, they use a read-modify-write pattern, therefore we should be careful not to pack bitfields that can be concurrently updated into the same storage unit. This split takes a binary approach: flags that are only modified pre/post open/close remain bitfields, flags modified from user action, including actions that reach across to another device (ex. reset) use dedicated storage units. Note mlx5_vhca_page_tracker.status is relocated to fill the alignment hole this split exposes. Bitfield justifications: migrate_cap: written only in mlx5vf_cmd_set_migratable() at probe chunk_mode: written only in mlx5vf_cmd_set_migratable() at probe mig_state_cap: written only in mlx5vf_cmd_set_migratable() at probe Dedicated storage units: mdev_detach: written in the VF attach/detach event notifier mlx5fv_vf_event() at runtime log_active: written in mlx5vf_start_page_tracker()/ mlx5vf_stop_page_tracker() during runtime dirty tracking deferred_reset: written in mlx5vf_state_mutex_unlock()/ mlx5vf_pci_aer_reset_done() during runtime reset handling is_err: set by tracker error handling and dirty-log polling at runtime object_changed: set by tracker event handling and cleared by dirty-log polling at runtime

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory per the references below.
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## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/1dd99b8f4e143592e12e5a77e7b538bc698116cb
- https://git.kernel.org/stable/c/f1db80a67da928a92ba460ede1be52d8941f46be
- https://git.kernel.org/stable/c/399d806f998f7a25405fc1b97227e579aead24af
- https://git.kernel.org/stable/c/7ed120b1a007bace57c461805519d70e1af44e59
- https://git.kernel.org/stable/c/39d163627b51886492bf31f66cb02c94613d2287
- https://git.kernel.org/stable/c/f2365a63b02ddea32e7db78b742c2503ec7b81f1

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