Executive brief
A vulnerability in the Broadcom GENET network driver used in devices like the Raspberry Pi 4 can cause network connectivity to fail. When certain power-saving features (Energy Efficient Ethernet) are active, the system may stop receiving data or experience a system crash. This can lead to a complete loss of network availability for affected devices.
Technical details
The vulnerability exists in the bcmgenet driver where enabling RBUF_EEE_EN and RBUF_PM_EN in the RBUF_ENERGY_CTRL register causes the RX path to fail on GENET hardware when MAC EEE becomes active. While the MAC continues to accept frames (causing buffer overflows), the RBUF stops forwarding them to DMA, resulting in a loss of RX traffic. On certain hardware configurations, such as the Raspberry Pi 4B, this state can trigger a paging fault in skb_release_data during an LPI exit. The fix involves ensuring these specific bits remain disabled across resets while leaving TX-side EEE functional.
Affected products
- Linux Linux Kernel 6ef398ea60d9 to 2040eb83f6ad
Timeline
- 2026-07-19: disclosed
- 2026-07-19: advisory
References
- https://git.kernel.org/stable/c/2040eb83f6ada148fb32dd98b943a498005d79f2
- https://git.kernel.org/stable/c/289499907399c5a9f2ed82cb34df49112bb8488f
- https://git.kernel.org/stable/c/3d4ef05266ab16d8ef7dd21658a557801eb78704
- https://git.kernel.org/stable/c/49bdf6bbb21b9c6e3f4d0c1910bf0ef98424be95
- https://git.kernel.org/stable/c/9a1730245e416d11ad5c0f2c100061d61cc43f60
- https://git.kernel.org/stable/c/a212fc08f5c48a16a94092bf0a9a8b7cf4483b11
- https://git.kernel.org/stable/c/b579f3a73da7a7e74213558f4cc3d865c30aaa78