cbcvebase.
CVE-2025-68232
published 2025-12-16

CVE-2025-68232: In the Linux kernel, the following vulnerability has been resolved: veth: more robust handing of race to avoid txq getting stuck Commit dc82a33297fc ("veth…

PriorityP340high7.5CVSS 3.1
AVNACLPRNUINSUCNINAH
EPSS
0.35%
27.5th percentile
In the Linux kernel, the following vulnerability has been resolved: veth: more robust handing of race to avoid txq getting stuck Commit dc82a33297fc ("veth: apply qdisc backpressure on full ptr_ring to reduce TX drops") introduced a race condition that can lead to a permanently stalled TXQ. This was observed in production on ARM64 systems (Ampere Altra Max). The race occurs in veth_xmit(). The producer observes a full ptr_ring and stops the queue (netif_tx_stop_queue()). The subsequent conditional logic, intended to re-wake the queue if the consumer had just emptied it (if (__ptr_ring_empty(...)) netif_tx_wake_queue()), can fail. This leads to a "lost wakeup" where the TXQ remains stopped (QUEUE_STATE_DRV_XOFF) and traffic halts. This failure is caused by an incorrect use of the __ptr_ring_empty() API from the producer side. As noted in kernel comments, this check is not guaranteed to be correct if a consumer is operating on another CPU. The empty test is based on ptr_ring->consumer_head, making it reliable only for the consumer. Using this check from the producer side is fundamentally racy. This patch fixes the race by adopting the more robust logic from an earlier version V4 of the patchset, which always flushed the peer: (1) In veth_xmit(), the racy conditional wake-up logic and its memory barrier are removed. Instead, after stopping the queue, we unconditionally call __veth_xdp_flush(rq). This guarantees that the NAPI consumer is scheduled, making it solely responsible for re-waking the TXQ. This handles the race where veth_poll() consumes all packets and completes NAPI *before* veth_xmit() on the producer side has called netif_tx_stop_queue. The __veth_xdp_flush(rq) will observe rx_notify_masked is false and schedule NAPI. (2) On the consumer side, the logic for waking the peer TXQ is moved out of veth_xdp_rcv() and placed at the end of the veth_poll() function. This placement is part of fixing the race, as the netif_tx_queue_stopped() check must occur a

Affected

8 ranges
VendorProductVersion rangeFixed in
debianlinux< linux 6.17.10-1 (forky)linux 6.17.10-1 (forky)
linuxlinux
linuxlinux>= 9fe31b3f314534e238aa6d0b6fb492134cbcf8be < dd419a3f2ebc18cc00bc32c57fd052d7a188b78bdd419a3f2ebc18cc00bc32c57fd052d7a188b78b
linuxlinux>= dc82a33297fc2c58cb0b2b008d728668d45c0f6a < 6c8a8b9257a660e622689e23c8fbad4ba2b561b96c8a8b9257a660e622689e23c8fbad4ba2b561b9
linuxlinux>= dc82a33297fc2c58cb0b2b008d728668d45c0f6a < 5442a9da69789741bfda39f34ee7f69552bf0c565442a9da69789741bfda39f34ee7f69552bf0c56
linuxlinux_kernel>= 0 < 6.17.10-16.17.10-1
linuxlinux_kernel>= 0 < 6.17.0-19.196.17.0-19.19
linuxlinux_kernel>= 6.16.0 < 6.17.106.17.10

CVSS provenance

nvdv3.17.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
osv7.2HIGH
vendor_ubuntu7.2HIGH
vendor_redhat5.5MEDIUM
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