Affected: Linux

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

net: bcmgenet: stop Tx NAPI before disabling the queues

bcmgenet_netif_stop() and the Wake-on-LAN branch of bcmgenet_suspend() both disable the Tx queues first and stop Tx NAPI several steps later. A completion in flight calls netif_tx_wake_queue() in between, and nothing stops the queue again, so a transmit can reach the rings after they have been freed.

Close is safe because dev_deactivate_many() stops the qdisc first. bcmgenet_suspend() does not, so stop Tx NAPI before the queues on both paths.

KASAN on a Raspberry Pi CM4, driven from an MTU change because suspend freezes user space before the callback runs:

BUG: KASAN: use-after-free in bcmgenet_xmit+0x17f8/0x2258 Write of size 8 at addr ffffff8055844a68 by task ksoftirqd/0/14 bcmgenet_xmit+0x17f8/0x2258 dev_hard_start_xmit+0x13c/0x588 sch_direct_xmit+0x108/0x340 __dev_queue_xmit+0x1190/0x3848