{"id":"CVE-2026-31691","title":"igb: remove napi_synchronize() in igb_down()","summary":"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 pollin…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= 2c6196013f84651772388a86dfd4bb033d0c0d45 < 4700471775746058c962ded6e659bf908fd76e13","Linux >= 2c6196013f84651772388a86dfd4bb033d0c0d45 < 27f5997686ee7fb7ac01be72b2010f168a3409fc","Linux >= 2c6196013f84651772388a86dfd4bb033d0c0d45 < b1e067240379f950a0022208e0685f3465c211cb","Linux 6.14"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2026-11-06T15:24:22.822570Z"},"published":"2026-04-27","updated":"2026-11-06","sourceUpdated":"2026-11-06T15:32:23.128Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-31691","references":[{"url":"https://git.kernel.org/stable/c/4700471775746058c962ded6e659bf908fd76e13"},{"url":"https://git.kernel.org/stable/c/27f5997686ee7fb7ac01be72b2010f168a3409fc"},{"url":"https://git.kernel.org/stable/c/b1e067240379f950a0022208e0685f3465c211cb"}],"tags":["cve.org"],"epss":0.00112,"epssPercentile":0.01403,"ingestedAt":"2026-11-06T15:54:04.045Z","slug":"CVE-2026-31691","body":"## Overview\n\nIn 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.\n\n## Affected\n\n- `Linux >= 2c6196013f84651772388a86dfd4bb033d0c0d45 < 4700471775746058c962ded6e659bf908fd76e13`\n- `Linux >= 2c6196013f84651772388a86dfd4bb033d0c0d45 < 27f5997686ee7fb7ac01be72b2010f168a3409fc`\n- `Linux >= 2c6196013f84651772388a86dfd4bb033d0c0d45 < b1e067240379f950a0022208e0685f3465c211cb`\n- `Linux 6.14`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}