CVE-2025-21954 Information

Description

In the Linux kernel the following vulnerability has been resolved:

netmem: prevent TX of unreadable skbs

Currently on stable trees we have support for netmem/devmem RX but not TX. It is not safe to forward/redirect an RX unreadable netmem packet into the device’s TX path as the device may call dma-mapping APIs on dma addrs that should not be passed to it.

Fix this by preventing the xmit of unreadable skbs.

Tested by configuring tc redirect:

sudo tc qdisc add dev eth1 ingress sudo tc filter add dev eth1 ingress protocol ip prio 1 flower ip_proto
tcp src_ip 192.168.1.12 action mirred egress redirect dev eth1

Before I see unreadable skbs in the driver’s TX path passed to dma mapping APIs.

After I don’t see unreadable skbs in the driver’s TX path passed to dma mapping APIs.

Reference

https://git.kernel.org/stable/c/1c17c8ced25c5fbe424c7ad7ea11d33014a986b1 https://git.kernel.org/stable/c/454825019d2f0c59e5174ece9e713f45ad80beff https://git.kernel.org/stable/c/f3600c867c99a2cc8038680ecf211089c50e7971