CVE-2024-50041

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.

Weakness

The product does not sufficiently track and release allocated memory after it has been used, making the memory unavailable for reallocation and reuse.

Affected Software

Potential Mitigations

• Choose a language or tool that provides automatic memory management, or makes manual memory management less error-prone.
• For example, glibc in Linux provides protection against free of invalid pointers.
• When using Xcode to target OS X or iOS, enable automatic reference counting (ARC) [REF-391].
• To help correctly and consistently manage memory when programming in C++, consider using a smart pointer class such as std::auto_ptr (defined by ISO/IEC ISO/IEC 14882:2003), std::shared_ptr and std::unique_ptr (specified by an upcoming revision of the C++ standard, informally referred to as C++ 1x), or equivalent solutions such as Boost.

References

• https://git.kernel.org/stable/c/703c4d820b31bcadf465288d5746c53445f02a55
• https://git.kernel.org/stable/c/8831abff1bd5b6bc8224f0c0671f46fbd702b5b2
• https://git.kernel.org/stable/c/9a9747288ba0a9ad4f5c9877f18dd245770ad64e
• https://git.kernel.org/stable/c/9db6ce9e2738b05a3672aff4d42169cf3bb5a3e3
• https://git.kernel.org/stable/c/dac6c7b3d33756d6ce09f00a96ea2ecd79fae9fb
• https://lists.debian.org/debian-lts-announce/2025/01/msg00001.html