{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2025-68232", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2025-12-16T13:41:40.258Z", "datePublished": "2025-12-16T14:04:12.624Z", "dateUpdated": "2026-08-05T12:10:19.353Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:10:19.353Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nveth: more robust handing of race to avoid txq getting stuck\n\nCommit dc82a33297fc (\"veth: apply qdisc backpressure on full ptr_ring to\nreduce TX drops\") introduced a race condition that can lead to a permanently\nstalled TXQ. This was observed in production on ARM64 systems (Ampere Altra\nMax).\n\nThe race occurs in veth_xmit(). The producer observes a full ptr_ring and\nstops the queue (netif_tx_stop_queue()). The subsequent conditional logic,\nintended to re-wake the queue if the consumer had just emptied it (if\n(__ptr_ring_empty(...)) netif_tx_wake_queue()), can fail. This leads to a\n\"lost wakeup\" where the TXQ remains stopped (QUEUE_STATE_DRV_XOFF) and\ntraffic halts.\n\nThis failure is caused by an incorrect use of the __ptr_ring_empty() API\nfrom the producer side. As noted in kernel comments, this check is not\nguaranteed to be correct if a consumer is operating on another CPU. The\nempty test is based on ptr_ring->consumer_head, making it reliable only for\nthe consumer. Using this check from the producer side is fundamentally racy.\n\nThis patch fixes the race by adopting the more robust logic from an earlier\nversion V4 of the patchset, which always flushed the peer:\n\n(1) In veth_xmit(), the racy conditional wake-up logic and its memory barrier\nare removed. Instead, after stopping the queue, we unconditionally call\n__veth_xdp_flush(rq). This guarantees that the NAPI consumer is scheduled,\nmaking it solely responsible for re-waking the TXQ.\n This handles the race where veth_poll() consumes all packets and completes\nNAPI *before* veth_xmit() on the producer side has called netif_tx_stop_queue.\nThe __veth_xdp_flush(rq) will observe rx_notify_masked is false and schedule\nNAPI.\n\n(2) On the consumer side, the logic for waking the peer TXQ is moved out of\nveth_xdp_rcv() and placed at the end of the veth_poll() function. This\nplacement is part of fixing the race, as the netif_tx_queue_stopped() check\nmust occur after rx_notify_masked is potentially set to false during NAPI\ncompletion.\n This handles the race where veth_poll() consumes all packets, but haven't\nfinished (rx_notify_masked is still true). The producer veth_xmit() stops the\nTXQ and __veth_xdp_flush(rq) will observe rx_notify_masked is true, meaning\nnot starting NAPI. Then veth_poll() change rx_notify_masked to false and\nstops NAPI. Before exiting veth_poll() will observe TXQ is stopped and wake\nit up." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "baseScore": 7.5, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:N - Unauthenticated Internet traffic routed, NATed, or bridged into a suitably configured container veth traverses the qdisc and reaches veth_xmit(). No local syscall or physical access is required.\nAC:L - Sustained or multi-flow traffic can fill the 256-entry ring while also driving its NAPI consumer, repeatedly creating the vulnerable interleaving. No uncontrollable memory layout or one-shot race is required.\nPR:N - The packet forwarding and bridge paths contain no capability or authentication check. The qdisc and NAPI/XDP configuration is a deployment prerequisite, not an attacker privilege requirement.\nUI:N - Exploitation requires only attacker-generated traffic and concurrent kernel packet processing. No victim action is necessary.\nS:U - The effect remains within the host kernel's veth networking component and does not cross a VM, IOMMU, or sandbox security boundary.\nC:N - The defect only leaves a transmit-queue state bit set and provides no memory disclosure or read primitive.\nI:N - There is no memory corruption, arbitrary write, packet-content modification, or control-flow influence.\nA:H - The lost wakeup can leave the TXQ stopped indefinitely; on the default single-queue veth this halts the link's transmit traffic and effectively makes the connected service unavailable until administrative recovery." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/net/veth.c" ], "versions": [ { "version": "9fe31b3f314534e238aa6d0b6fb492134cbcf8be", "lessThan": "dd419a3f2ebc18cc00bc32c57fd052d7a188b78b", "status": "affected", "versionType": "git" }, { "version": "dc82a33297fc2c58cb0b2b008d728668d45c0f6a", "lessThan": "6c8a8b9257a660e622689e23c8fbad4ba2b561b9", "status": "affected", "versionType": "git" }, { "version": "dc82a33297fc2c58cb0b2b008d728668d45c0f6a", "lessThan": "5442a9da69789741bfda39f34ee7f69552bf0c56", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/net/veth.c" ], "versions": [ { "version": "6.16", "status": "affected" }, { "version": "0", "lessThan": "6.16", "status": "unaffected", "versionType": "semver" }, { "version": "6.17.10", "lessThanOrEqual": "6.17.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.16", "versionEndExcluding": "6.17.10" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.16", "versionEndExcluding": "6.18" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/dd419a3f2ebc18cc00bc32c57fd052d7a188b78b" }, { "url": "https://git.kernel.org/stable/c/6c8a8b9257a660e622689e23c8fbad4ba2b561b9" }, { "url": "https://git.kernel.org/stable/c/5442a9da69789741bfda39f34ee7f69552bf0c56" } ], "title": "veth: more robust handing of race to avoid txq getting stuck", "x_generator": { "engine": "bippy-1.2.0" } } } }