Affected: Linux

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

qede: sync udp_tunnel ports outside qede_lock in the recovery path

A TX timeout on a qede NIC that has VXLAN/GENEVE tunnel ports configured wedges the rtnetlink control plane of the whole machine:

NETDEV WATCHDOG: ens6f1 (qede): transmit queue 2 timed out 10226 ms [qede_tx_timeout:586(ens6f1)]TX timeout on queue 2! [qede_recovery_handler:2665(ens6f0)]Starting a recovery process

The recovery path deadlocks on the driver's own mutex:

qede_sp_task rtnl_lock() mutex_lock(&edev->qede_lock) <- taken qede_recovery_handler qede_load udp_tunnel_nic_reset_ntf __udp_tunnel_nic_device_sync info->sync_table == qede_udp_tunnel_sync mutex_lock(&edev->qede_lock) <- same task: deadlock

The mutex is not recursive, so the kworker blocks on itself with rtnl_lock held, and neither lock is ever released. Every task that calls rtnl_lock() afterwards (ip, ovs-vswitchd, lldpad, IPv6 addrconf, sshd) blocks forever while the node still answers ping. In a vmcore from an affected production node rtnl_mutex.owner decodes to the very kworker blocked at the innermost mutex_lock() above.

Re-sync the tunnel ports from qede_sp_task() after the internal lock is dropped, still under rtnl_lock as the udp_tunnel API requires. This mirrors qede_open(), which calls udp_tunnel_nic_reset_ntf() under rtnl without the internal lock.

qede_recovery_handler() now returns whether it has successfu…