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  - net: thunderbolt: Tear down DMA paths before stopping the rings tbnet_tear_down() stops both rings and     frees their frame buffers before calling tb_xdomain_disable_paths(). tb_ring_stop() zeroes the ring's     descriptor base and tbnet_free_buffers() unmaps and frees the pages the frames sit in, so by the time
    __tb_path_deactivate_hop() polls the hop's 'pending' bit, anything still in flight has nowhere to drain     to. The teardown sequence has been in this order since the driver was added. The setup path has not:
    commit ff7cd07f3064 (net: thunderbolt: Enable DMA paths only after rings are enabled) moved the path     enable to the end of tbnet_connected_work() and documented why: /* Both logins successful so enable the     rings, high-speed DMA * paths and start the network device queue. * * Note we enable the DMA paths last to     make sure we have primed * the Rx ring before any incoming packets are allowed to * arrive. */ Teardown     was never updated to match, so the rings and the paths now come down in the same order they go up instead     of in reverse. On an ASMedia ASM4242 host router the 'pending' bit then never clears: every teardown burns     the full 500 ms timeout and __tb_path_deactivate_hop() returns -ETIMEDOUT. Raising the timeout to 5 s does     not help, so the hop is not slow to drain, it never drains at all. The failure is invisible above the     thunderbolt core. __tb_path_deactivate_hops() is void and only calls tb_port_warn(); tb_path_deactivate(),     tb_tunnel_deactivate() and __tb_disconnect_xdomain_paths() are void as well, and     tb_disconnect_xdomain_paths() ends in an unconditional return 0. So tb_xdomain_disable_paths() reports     success and the netdev_warn() below it never fires. Repeated teardowns eventually take the XDomain control     channel down, after which the peer node is gone and only a power cycle brings the controller back.
    Deactivating the paths first fixes it. Measured with kretprobes on a stock v6.17 tree with no other     patches applied, on a link that was up and had just carried traffic: before: __tb_path_deactivate_hop()     returns 0 for the first hop, then -ETIMEDOUT for the second 500335 us later after: 0 for both, 525 us     apart Alternating the two orderings ABBA over three load levels, four teardowns per arm: every teardown     failed before the change (21 of 21 that ran), none failed after (0 of 24). The before arms ran short     because the link died partway through. The same split shows up when the interface is enslaved to a bond     instead of just brought down, which is how I ran into this in the first place. Throughput and latency     after the change are unchanged. Hosts whose routers drain the hop despite the stale descriptor base see no     functional difference, since the paths end up deactivated either way. (CVE-2026-74691)

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Linux Distros Unpatched Vulnerability : CVE-2026-74691

high Nessus Plugin ID 338962

Version 1.2