Description

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

net: avoid race between device unregistration and ethnl ops

The following trace can be seen if a device is being unregistered while
its number of channels are being modified.

DEBUG_LOCKS_WARN_ON(lock->magic != lock)
WARNING: CPU: 3 PID: 3754 at kernel/locking/mutex.c:564 __mutex_lock+0xc8a/0x1120
CPU: 3 UID: 0 PID: 3754 Comm: ethtool Not tainted 6.13.0-rc6+ #771
RIP: 0010:__mutex_lock+0xc8a/0x1120
Call Trace:

ethtool_check_max_channel+0x1ea/0x880
ethnl_set_channels+0x3c3/0xb10
ethnl_default_set_doit+0x306/0x650
genl_family_rcv_msg_doit+0x1e3/0x2c0
genl_rcv_msg+0x432/0x6f0
netlink_rcv_skb+0x13d/0x3b0
genl_rcv+0x28/0x40
netlink_unicast+0x42e/0x720
netlink_sendmsg+0x765/0xc20
__sys_sendto+0x3ac/0x420
__x64_sys_sendto+0xe0/0x1c0
do_syscall_64+0x95/0x180
entry_SYSCALL_64_after_hwframe+0x76/0x7e

This is because unregister_netdevice_many_notify might run before the
rtnl lock section of ethnl operations, eg. set_channels in the above
example. In this example the rss lock would be destroyed by the device
unregistration path before being used again, but in general running
ethnl operations while dismantle has started is not a good idea.

Fix this by denying any operation on devices being unregistered. A check
was already there in ethnl_ops_begin, but not wide enough.

Note that the same issue cannot be seen on the ioctl version
(__dev_ethtool) because the devic...

Classification

CVE ID: CVE-2025-21701

Affected Products

Vendor: Linux

Product: Linux

Exploit Prediction Scoring System (EPSS)

EPSS Score: 0.04% (probability of being exploited)

EPSS Percentile: 12.91% (scored less or equal to compared to others)

EPSS Date: 2025-03-14 (when was this score calculated)

References

https://git.kernel.org/stable/c/2f29127e94ae9fdc7497331003d6860e9551cdf3
https://git.kernel.org/stable/c/b382ab9b885cbb665e0e70a727f101c981b4edf3
https://git.kernel.org/stable/c/4dc880245f9b529fa8f476b5553c799d2848b47b
https://git.kernel.org/stable/c/12e070eb6964b341b41677fd260af5a305316a1f

Timeline