CVE-2026-31644

In the Linux kernel, the following vulnerability has been resolved:

net: lan966x: fix use-after-free and leak in lan966x_fdma_reload()

When lan966x_fdma_reload() fails to allocate new RX buffers, the restore path restarts DMA using old descriptors whose pages were already freed via lan966x_fdma_rx_free_pages(). Since page_pool_put_full_page() can release pages back to the buddy allocator, the hardware may DMA into memory now owned by other kernel subsystems.

Additionally, on the restore path, the newly created page pool (if allocation partially succeeded) is overwritten without being destroyed, leaking it.

Fix both issues by deferring the release of old pages until after the new allocation succeeds. Save the old page array before the allocation so old pages can be freed on the success path. On the failure path, the old descriptors, pages and page pool are all still valid, making the restore safe. Also ensure the restore path re-enables NAPI and wakes the netdev, matching the success path.

Weakness

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory “belongs” to the code that operates on the new pointer.

Affected Software

Potential Mitigations

References

• https://git.kernel.org/stable/c/59c3d55a946cacdb4181600723c20ac4f4c20c84
• https://git.kernel.org/stable/c/691082c0b93c13a5e068c0905f673060bddc204e
• https://git.kernel.org/stable/c/92a673019943770930e2a8bfd52e1aad47a1fc1f
• https://git.kernel.org/stable/c/9950e9199b3dfdfbde0b8d96ba947d7b11243801