CVE-2025-37920: xsk: Fix race condition in AF_XDP generic RX path
Description
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.
Classification
CVE ID: CVE-2025-37920
Affected Products
Vendor: Linux
Product: Linux
Exploit Prediction Scoring System (EPSS)
EPSS Score: 0.02% (probability of being exploited)
EPSS Percentile: 4.26% (scored less or equal to compared to others)
EPSS Date: 2025-06-18 (when was this score calculated)
References
https://nvd.nist.gov/vuln/detail/CVE-2025-37920https://git.kernel.org/stable/c/65d3c570614b892257dc58a1b202908242ecf8fd
https://git.kernel.org/stable/c/75a240a3e8abf17b9e00b0ef0492b1bbaa932251
https://git.kernel.org/stable/c/a1356ac7749cafc4e27aa62c0c4604b5dca4983e