In 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.
Advisories

No advisories yet.

Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Tue, 28 Apr 2026 00:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-833
References
Metrics threat_severity

None

cvssV3_1

{'score': 5.5, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}

threat_severity

Moderate


Mon, 27 Apr 2026 18:00:00 +0000

Type Values Removed Values Added
Description In 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.
Title igb: remove napi_synchronize() in igb_down()
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-04-27T17:34:29.738Z

Reserved: 2026-03-09T15:48:24.131Z

Link: CVE-2026-31691

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-04-27T18:16:54.610

Modified: 2026-04-27T18:32:22.917

Link: CVE-2026-31691

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-04-27T00:00:00Z

Links: CVE-2026-31691 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-04-28T00:30:15Z

Weaknesses