CVE-2024-50041 in Linux
Summary
by MITRE • 10/21/2024
In the Linux kernel, the following vulnerability has been resolved:
i40e: Fix macvlan leak by synchronizing access to mac_filter_hash
This patch addresses a macvlan leak issue in the i40e driver caused by concurrent access to vsi->mac_filter_hash. The leak occurs when multiple threads attempt to modify the mac_filter_hash simultaneously, leading to inconsistent state and potential memory leaks.
To fix this, we now wrap the calls to i40e_del_mac_filter() and zeroing vf->default_lan_addr.addr with spin_lock/unlock_bh(&vsi->mac_filter_hash_lock), ensuring atomic operations and preventing concurrent access.
Additionally, we add lockdep_assert_held(&vsi->mac_filter_hash_lock) in i40e_add_mac_filter() to help catch similar issues in the future.
Reproduction steps: 1. Spawn VFs and configure port vlan on them. 2. Trigger concurrent macvlan operations (e.g., adding and deleting portvlan and/or mac filters). 3. Observe the potential memory leak and inconsistent state in the mac_filter_hash.
This synchronization ensures the integrity of the mac_filter_hash and prevents the described leak.
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Analysis
by VulDB Data Team • 03/22/2026
The vulnerability identified as CVE-2024-50041 represents a critical race condition within the Intel i40e network driver implementation in the Linux kernel. This issue manifests as a macvlan leak that occurs when multiple threads simultaneously attempt to access and modify the vsi->mac_filter_hash data structure. The problem stems from insufficient synchronization mechanisms during concurrent operations, creating a scenario where memory management becomes corrupted due to inconsistent state modifications. The vulnerability specifically impacts virtual function (VF) configurations where port VLAN operations and MAC filter manipulations occur concurrently, leading to potential memory leaks and system instability.
The technical flaw resides in the lack of proper atomic operations when handling MAC filter modifications within the i40e driver's virtual switch instance (VSI). When multiple threads execute i40e_del_mac_filter() and operations that zero vf->default_lan_addr.addr simultaneously, the mac_filter_hash structure becomes corrupted due to missing synchronization primitives. This race condition allows for memory references to become invalid or lost, resulting in the described macvlan leak. The vulnerability operates at the kernel level where concurrent access patterns are not properly protected, creating a situation where the kernel's memory management system fails to maintain consistent state during parallel operations.
The operational impact of this vulnerability extends beyond simple memory leaks to potentially compromise network functionality and system stability. When concurrent MAC filter operations occur during VF port VLAN configuration, the system may experience degraded network performance, intermittent connectivity issues, or complete network interface failures. The inconsistent state in mac_filter_hash can lead to unpredictable behavior in network packet forwarding and filtering operations, particularly in virtualized environments where multiple VFs share the same physical network interface. This vulnerability is particularly concerning in high-throughput environments where concurrent network operations are common, as it can lead to cascading failures and system resource exhaustion.
The mitigation implemented in this patch addresses the core synchronization issue by introducing proper spin lock mechanisms around critical sections of code that modify the mac_filter_hash structure. The solution employs spin_lock/unlock_bh(&vsi->mac_filter_hash_lock) to ensure atomic operations during i40e_del_mac_filter() calls and default address zeroing operations. Additionally, the patch incorporates lockdep_assert_held(&vsi->mac_filter_hash_lock) within i40e_add_mac_filter() to provide additional runtime checking that helps prevent similar synchronization issues from emerging in future code modifications. This approach aligns with common security best practices for concurrent programming and follows the principles outlined in CWE-362, which addresses race conditions in concurrent systems. The fix directly addresses the ATT&CK technique T1484.001 by preventing unauthorized modifications to system resources that could lead to memory corruption and denial of service conditions.
The reproduction of this vulnerability requires specific conditions involving virtual function creation and concurrent port VLAN operations, making it particularly relevant to virtualized network environments. The vulnerability demonstrates the importance of proper kernel synchronization mechanisms in high-performance network drivers where multiple threads may simultaneously access shared data structures. This issue highlights the broader challenge of maintaining memory integrity in complex kernel subsystems where concurrent access patterns are common. The fix ensures that all modifications to the mac_filter_hash structure occur within properly protected critical sections, preventing the memory leak scenario while maintaining the driver's functionality and performance characteristics.