GHSA-3MF8-6WC5-2F9C
Vulnerability from github – Published: 2026-04-27 18:32 – Updated: 2026-05-06 21:31In the Linux kernel, the following vulnerability has been resolved:
igb: remove napi_synchronize() in igb_down()
When an AF_XDP zero-copy application terminates abruptly (e.g., kill -9), the XSK buffer pool is destroyed but NAPI polling continues. igb_clean_rx_irq_zc() repeatedly returns the full budget, preventing napi_complete_done() from clearing NAPI_STATE_SCHED.
igb_down() calls napi_synchronize() before napi_disable() for each queue vector. napi_synchronize() spins waiting for NAPI_STATE_SCHED to clear, which never happens. igb_down() blocks indefinitely, the TX watchdog fires, and the TX queue remains permanently stalled.
napi_disable() already handles this correctly: it sets NAPI_STATE_DISABLE. After a full-budget poll, __napi_poll() checks napi_disable_pending(). If set, it forces completion and clears NAPI_STATE_SCHED, breaking the loop that napi_synchronize() cannot.
napi_synchronize() was added in commit 41f149a285da ("igb: Fix possible panic caused by Rx traffic arrival while interface is down"). napi_disable() provides stronger guarantees: it prevents further scheduling and waits for any active poll to exit. Other Intel drivers (ixgbe, ice, i40e) use napi_disable() without a preceding napi_synchronize() in their down paths.
Remove redundant napi_synchronize() call and reorder napi_disable() before igb_set_queue_napi() so the queue-to-NAPI mapping is only cleared after polling has fully stopped.
{
"affected": [],
"aliases": [
"CVE-2026-31691"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-04-27T18:16:54Z",
"severity": "MODERATE"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nigb: remove napi_synchronize() in igb_down()\n\nWhen an AF_XDP zero-copy application terminates abruptly (e.g., kill -9),\nthe XSK buffer pool is destroyed but NAPI polling continues.\nigb_clean_rx_irq_zc() repeatedly returns the full budget, preventing\nnapi_complete_done() from clearing NAPI_STATE_SCHED.\n\nigb_down() calls napi_synchronize() before napi_disable() for each queue\nvector. napi_synchronize() spins waiting for NAPI_STATE_SCHED to clear,\nwhich never happens. igb_down() blocks indefinitely, the TX watchdog\nfires, and the TX queue remains permanently stalled.\n\nnapi_disable() already handles this correctly: it sets NAPI_STATE_DISABLE.\nAfter a full-budget poll, __napi_poll() checks napi_disable_pending(). If\nset, it forces completion and clears NAPI_STATE_SCHED, breaking the loop\nthat napi_synchronize() cannot.\n\nnapi_synchronize() was added in commit 41f149a285da (\"igb: Fix possible\npanic caused by Rx traffic arrival while interface is down\").\nnapi_disable() provides stronger guarantees: it prevents further\nscheduling and waits for any active poll to exit.\nOther Intel drivers (ixgbe, ice, i40e) use napi_disable() without a\npreceding napi_synchronize() in their down paths.\n\nRemove redundant napi_synchronize() call and reorder napi_disable()\nbefore igb_set_queue_napi() so the queue-to-NAPI mapping is only\ncleared after polling has fully stopped.",
"id": "GHSA-3mf8-6wc5-2f9c",
"modified": "2026-05-06T21:31:30Z",
"published": "2026-04-27T18:32:09Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-31691"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/27f5997686ee7fb7ac01be72b2010f168a3409fc"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/4700471775746058c962ded6e659bf908fd76e13"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/b1e067240379f950a0022208e0685f3465c211cb"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.