ghsa-vqg7-j8rg-9mw8
Vulnerability from github
In the Linux kernel, the following vulnerability has been resolved:
rcu: Fix rcu_read_unlock() deadloop due to IRQ work
During rcu_read_unlock_special(), if this happens during irq_exit(), we can lockup if an IPI is issued. This is because the IPI itself triggers the irq_exit() path causing a recursive lock up.
This is precisely what Xiongfeng found when invoking a BPF program on the trace_tick_stop() tracepoint As shown in the trace below. Fix by managing the irq_work state correctly.
irq_exit() __irq_exit_rcu() / in_hardirq() returns false after this / preempt_count_sub(HARDIRQ_OFFSET) tick_irq_exit() tick_nohz_irq_exit() tick_nohz_stop_sched_tick() trace_tick_stop() / a bpf prog is hooked on this trace point / __bpf_trace_tick_stop() bpf_trace_run2() rcu_read_unlock_special() / will send a IPI to itself / irq_work_queue_on(&rdp->defer_qs_iw, rdp->cpu);
A simple reproducer can also be obtained by doing the following in tick_irq_exit(). It will hang on boot without the patch:
static inline void tick_irq_exit(void) { + rcu_read_lock(); + WRITE_ONCE(current->rcu_read_unlock_special.b.need_qs, true); + rcu_read_unlock(); +
[neeraj: Apply Frederic's suggested fix for PREEMPT_RT]
{
"affected": [],
"aliases": [
"CVE-2025-39744"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-09-11T17:15:37Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nrcu: Fix rcu_read_unlock() deadloop due to IRQ work\n\nDuring rcu_read_unlock_special(), if this happens during irq_exit(), we\ncan lockup if an IPI is issued. This is because the IPI itself triggers\nthe irq_exit() path causing a recursive lock up.\n\nThis is precisely what Xiongfeng found when invoking a BPF program on\nthe trace_tick_stop() tracepoint As shown in the trace below. Fix by\nmanaging the irq_work state correctly.\n\nirq_exit()\n __irq_exit_rcu()\n /* in_hardirq() returns false after this */\n preempt_count_sub(HARDIRQ_OFFSET)\n tick_irq_exit()\n tick_nohz_irq_exit()\n\t tick_nohz_stop_sched_tick()\n\t trace_tick_stop() /* a bpf prog is hooked on this trace point */\n\t\t __bpf_trace_tick_stop()\n\t\t bpf_trace_run2()\n\t\t\t rcu_read_unlock_special()\n /* will send a IPI to itself */\n\t\t\t irq_work_queue_on(\u0026rdp-\u003edefer_qs_iw, rdp-\u003ecpu);\n\nA simple reproducer can also be obtained by doing the following in\ntick_irq_exit(). It will hang on boot without the patch:\n\n static inline void tick_irq_exit(void)\n {\n +\trcu_read_lock();\n +\tWRITE_ONCE(current-\u003ercu_read_unlock_special.b.need_qs, true);\n +\trcu_read_unlock();\n +\n\n[neeraj: Apply Frederic\u0027s suggested fix for PREEMPT_RT]",
"id": "GHSA-vqg7-j8rg-9mw8",
"modified": "2025-09-11T18:35:51Z",
"published": "2025-09-11T18:35:51Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-39744"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/1cfa244f7198d325594e627574930b7b91df5bfe"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/56c5ef194f4509df63fc0f7a91ea5973ce479b1e"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/b41642c87716bbd09797b1e4ea7d904f06c39b7b"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/ddebb2a7677673cf4438a04e1a48b8ed6b0c8e9a"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e7a375453cca2b8a0d2fa1b82b913f3fed7c0507"
}
],
"schema_version": "1.4.0",
"severity": []
}
Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
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