CVE-2026-64472
Received Received - Intake

Race Condition in Linux Kernel VFIO MLX5 Driver

Publication date: 2026-07-25

Last updated on: 2026-07-25

Assigner: kernel.org

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

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Meta Information

Published
2026-07-25
Last Modified
2026-07-25
Generated
2026-07-25
AI Q&A
2026-07-25
EPSS Evaluated
N/A
NVD
CVE-2026-64472
EUVD
EUVD-2026-48816

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *

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Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability in the Linux kernel involves improper handling of bitfields in the vfio/mlx5 driver. Bitfield operations are not atomic and use a read-modify-write pattern, which can lead to race conditions if multiple threads or processes modify the same storage unit concurrently. The fix reorganizes the struct layout to separate bitfields that are modified at different times, reducing the risk of such race conditions.

Detection Guidance

This vulnerability is specific to the Linux kernel's VFIO/MLX5 driver and involves racy bitfield operations. Detection requires checking kernel logs for MLX5 VFIO-related errors or kernel panics. Use commands like dmesg | grep mlx5 or journalctl -k | grep mlx5 to inspect kernel logs for suspicious activity.

Impact Analysis

If exploited, this vulnerability could allow an attacker to cause unexpected behavior in the system, such as crashes or data corruption, due to race conditions in the vfio/mlx5 driver. This might affect virtualization environments using this driver, potentially leading to denial of service or privilege escalation.

Mitigation Strategies

Update your Linux kernel to the latest stable version that includes the fix for this vulnerability. If immediate patching is not possible, consider disabling the VFIO/MLX5 driver if not in use. Monitor kernel logs for any signs of exploitation or instability.

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