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CVE PROGRAM SOURCE RECORDUnscored

CVE-2025-21681

openvswitch: fix lockup on tx to unregistering netdev with carrier

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Status
Published
Published
Updated
Assigning organization
Linux

Description

In the Linux kernel, the following vulnerability has been resolved: openvswitch: fix lockup on tx to unregistering netdev with carrier Commit in a fixes tag attempted to fix the issue in the following sequence of calls: do_output -> ovs_vport_send -> dev_queue_xmit -> __dev_queue_xmit -> netdev_core_pick_tx -> skb_tx_hash When device is unregistering, the 'dev->real_num_tx_queues' goes to zero and the 'while (unlikely(hash >= qcount))' loop inside the 'skb_tx_hash' becomes infinite, locking up the core forever. But unfortunately, checking just the carrier status is not enough to fix the issue, because some devices may still be in unregistering state while reporting carrier status OK. One example of such device is a net/dummy. It sets carrier ON on start, but it doesn't implement .ndo_stop to set the carrier off. And it makes sense, because dummy doesn't really have a carrier. Therefore, while this device is unregistering, it's still easy to hit the infinite loop in the skb_tx_hash() from the OVS datapath. There might be other drivers that do the same, but dummy by itself is important for the OVS ecosystem, because it is frequently used as a packet sink for tcpdump while debugging OVS deployments. And when the issue is hit, the only way to recover is to reboot. Fix that by also checking if the device is running. The running state is handled by the net core during unregistering, so it covers unregistering case better, and we don't really need to send packets to devices that are not running anyway. While only checking the running state might be enough, the carrier check is preserved. The running and the carrier states seem disjoined throughout the code and different drivers. And other core functions like __dev_direct_xmit() check both before attempting to transmit a packet. So, it seems safer to check both flags in OVS as well.

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

Linux Linux

Default version status: unaffected

  • 9b0dd09c1ceb35950d2884848099fccc9ec9a123 to < b5c73fc92f8d15c16e5dc87b5c17d2abf1e6d092affected
  • 284be5db6c8d06d247ed056cfc448c4f79bbb16c to < 87fcf0d137c770e6040ebfdb0abd8e7dd481b504affected
  • 5efcb301523baacd98a47553d4996e924923114d to < 930268823f6bccb697aa5d2047aeffd4a497308caffected
  • 644b3051b06ba465bc7401bfae9b14963cbc8c1c to < ea9e990356b7bee95440ba0e6e83cc4d701afacaaffected
  • 066b86787fa3d97b7aefb5ac0a99a22dad2d15f8 to < ea966b6698785fb9cd0fdb867acd91b222e4723faffected
  • 066b86787fa3d97b7aefb5ac0a99a22dad2d15f8 to < 82f433e8dd0629e16681edf6039d094b5518d8edaffected
  • 066b86787fa3d97b7aefb5ac0a99a22dad2d15f8 to < 47e55e4b410f7d552e43011baa5be1aab4093990affected
  • 56252da41426f3d01957456f13caf46ce670ea29affected
  • 6.1.25 to < 6.1.127affected
  • 6.2.12 to < 6.3affected

Linux Linux

Default version status: affected

  • 6.3affected
  • 0 to < 6.3unaffected
  • 6.1.127 to ≤ 6.1.*unaffected
  • 6.6.74 to ≤ 6.6.*unaffected
  • 6.12.11 to ≤ 6.12.*unaffected
  • 6.13 to ≤ *unaffected

References