cbcvebase.
CVE-2025-21681
published 2025-01-31

CVE-2025-21681: 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…

PriorityP422medium5.5CVSS 3.1
AVLACLPRLUINSUCNINAH
EPSS
0.20%
10.1th percentile
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

21 ranges
VendorProductVersion rangeFixed in
debianlinux< linux 6.1.128-1 (bookworm)linux 6.1.128-1 (bookworm)
debianlinux-6.1< linux 6.1.128-1 (bookworm)linux 6.1.128-1 (bookworm)
linuxlinux
linuxlinux
linuxlinux>= 066b86787fa3d97b7aefb5ac0a99a22dad2d15f8 < ea966b6698785fb9cd0fdb867acd91b222e4723fea966b6698785fb9cd0fdb867acd91b222e4723f
linuxlinux>= 066b86787fa3d97b7aefb5ac0a99a22dad2d15f8 < 82f433e8dd0629e16681edf6039d094b5518d8ed82f433e8dd0629e16681edf6039d094b5518d8ed
linuxlinux>= 066b86787fa3d97b7aefb5ac0a99a22dad2d15f8 < 47e55e4b410f7d552e43011baa5be1aab409399047e55e4b410f7d552e43011baa5be1aab4093990
linuxlinux>= 284be5db6c8d06d247ed056cfc448c4f79bbb16c < 87fcf0d137c770e6040ebfdb0abd8e7dd481b50487fcf0d137c770e6040ebfdb0abd8e7dd481b504
linuxlinux>= 5efcb301523baacd98a47553d4996e924923114d < 930268823f6bccb697aa5d2047aeffd4a497308c930268823f6bccb697aa5d2047aeffd4a497308c
linuxlinux>= 6.1.25 < 6.1.1276.1.127
linuxlinux>= 6.2.12 < 6.36.3
linuxlinux>= 644b3051b06ba465bc7401bfae9b14963cbc8c1c < ea9e990356b7bee95440ba0e6e83cc4d701afacaea9e990356b7bee95440ba0e6e83cc4d701afaca
linuxlinux>= 9b0dd09c1ceb35950d2884848099fccc9ec9a123 < b5c73fc92f8d15c16e5dc87b5c17d2abf1e6d092b5c73fc92f8d15c16e5dc87b5c17d2abf1e6d092
linuxlinux_kernel
linuxlinux_kernel>= 0 < 6.1.128-16.1.128-1
linuxlinux_kernel>= 0 < 6.12.11-16.12.11-1
linuxlinux_kernel>= 0 < 6.12.11-16.12.11-1
linuxlinux_kernel>= 0 < 6.8.0-62.656.8.0-62.65
linuxlinux_kernel>= 6.1.25 < 6.1.1276.1.127
linuxlinux_kernel>= 6.2.12 < 6.6.746.6.74
linuxlinux_kernel>= 6.7 < 6.12.116.12.11

CVSS provenance

nvdv3.15.5MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
osv5.9MEDIUM
vendor_ubuntu5.9MEDIUM
vendor_debian5.5MEDIUM
vendor_redhat5.5MEDIUM
Stop checking back — get the weekly exploitation signal.

Every Monday: what got weaponized or added to CISA KEV in the last seven days — each CVE cross-linked to its PoC, Nuclei template, and detection rule. Free, one email a week, unsubscribe in one click.