In the Linux kernel, the following vulnerability has been resolved: net: dsa: remove redundant netdev_lock_ops() from conduit ethtool ops DSA replaces the conduit (master) device's ethtool_ops with its own wrappers that aggregate stats from both the conduit and DSA switch ports. Taking the lock again inside the DSA wrappers causes a deadlock. Stumbled upon this when booting qemu with fbnic and CONFIG_NET_DSA_LOOP=y (which looks like some kind of testing device that auto-populates the ports of eth0). `ethtool -i` is enough to deadlock. This means we have basically zero coverage for DSA stuff with real ops locked devs. Remove the redundant netdev_lock_ops()/netdev_unlock_ops() calls from the DSA conduit ethtool wrappers.
https://git.kernel.org/stable/c/abe91fd045874d21834482adcd7a9693e7377056
https://git.kernel.org/stable/c/74d64ae4254e99ef8c8215b057a76edac82c5f99
https://git.kernel.org/stable/c/0f99e0c3e19badaf3fdced0d3feba623e59eed41