GHSA-8W3X-69PJ-572X
Vulnerability from github – Published: 2026-09-04 18:31 – Updated: 2026-09-04 18:31In the Linux kernel, the following vulnerability has been resolved:
tipc: avoid busy looping in tipc_exit_net()
Blamed commit introduced a busy-wait loop in tipc_exit_net() to wait for pending UDP bearer cleanup works to complete:
while (atomic_read(&tn->wq_count))
cond_resched();
This loop can busy-wait for a long time if cond_resched() is a NOP. This typically happens if the netns exit is executed by a high priority task, or under kernels configured without preemption (CONFIG_PREEMPT_NONE). In such cases, it wastes CPU cycles and can lead to soft lockups.
Fix this by replacing the busy loop with wait_var_event(), allowing the thread to sleep properly until the work queue count reaches zero.
Accordingly, update cleanup_bearer() to use atomic_dec_and_test() and wake_up_var() to wake up the waiter when the count drops to zero.
This uses the global wait queue hash table, avoiding the need to bloat struct tipc_net with a wait_queue_head_t. The atomic_dec_and_test() provides the necessary memory barrier to ensure the wakeup is not missed.
{
"affected": [],
"aliases": [
"CVE-2026-80866"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-04T17:16:58Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\ntipc: avoid busy looping in tipc_exit_net()\n\nBlamed commit introduced a busy-wait loop in tipc_exit_net()\nto wait for pending UDP bearer cleanup works to complete:\n\n while (atomic_read(\u0026tn-\u003ewq_count))\n cond_resched();\n\nThis loop can busy-wait for a long time if cond_resched() is a NOP. This\ntypically happens if the netns exit is executed by a high priority task,\nor under kernels configured without preemption (CONFIG_PREEMPT_NONE). In\nsuch cases, it wastes CPU cycles and can lead to soft lockups.\n\nFix this by replacing the busy loop with wait_var_event(), allowing the\nthread to sleep properly until the work queue count reaches zero.\n\nAccordingly, update cleanup_bearer() to use atomic_dec_and_test() and\nwake_up_var() to wake up the waiter when the count drops to zero.\n\nThis uses the global wait queue hash table, avoiding the need to bloat\nstruct tipc_net with a wait_queue_head_t. The atomic_dec_and_test()\nprovides the necessary memory barrier to ensure the wakeup is not missed.",
"id": "GHSA-8w3x-69pj-572x",
"modified": "2026-09-04T18:31:31Z",
"published": "2026-09-04T18:31:31Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-80866"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/522d1d950b9e3b68190a6de7534827c8dccedb73"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/c1481c94e74c955e0448ddf46b8615a44d840c1e"
}
],
"schema_version": "1.4.0",
"severity": []
}
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