CVE-2025-37920

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

xsk: Fix race condition in AF_XDP generic RX path

Move rx_lock from xsk_socket to xsk_buff_pool.

Fix synchronization for shared umem mode in

generic RX path where multiple sockets share

single xsk_buff_pool.

RX queue is exclusive to xsk_socket, while FILL

queue can be shared between multiple sockets.

This could result in race condition where two

CPU cores access RX path of two different sockets

sharing the same umem.

Protect both queues by acquiring spinlock in shared

xsk_buff_pool.

Lock contention may be minimized in the future by some

per-thread FQ buffering.

It's safe and necessary to move spin_lock_bh(rx_lock)

after xsk_rcv_check():

* xs->pool and spinlock_init is synchronized by

xsk_bind() -> xsk_is_bound() memory barriers.

* xsk_rcv_check() may return true at the moment

of xsk_release() or xsk_unbind_dev(),

however this will not cause any data races or

race conditions. xsk_unbind_dev() removes xdp

socket from all maps and waits for completion

of all outstanding rx operations. Packets in

RX path will either complete safely or drop.