CVE-2025-39744 (GCVE-0-2025-39744)
Vulnerability from cvelistv5
Published
2025-09-11 16:52
Modified
2025-09-11 16:52
Severity ?
VLAI Severity ?
EPSS score ?
Summary
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]
References
Impacted products
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"kernel/rcu/tree.h",
"kernel/rcu/tree_plugin.h"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
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"versionType": "git"
},
{
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"versionType": "git"
},
{
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"versionType": "git"
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{
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"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
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"kernel/rcu/tree_plugin.h"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"version": "6.6.103",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.43",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.15.*",
"status": "unaffected",
"version": "6.15.11",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.16.*",
"status": "unaffected",
"version": "6.16.2",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "6.17-rc1",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
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"vulnerable": true
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{
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"versionEndExcluding": "6.12.43",
"vulnerable": true
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{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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{
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{
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}
],
"negate": false,
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}
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}
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"descriptions": [
{
"lang": "en",
"value": "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]"
}
],
"providerMetadata": {
"dateUpdated": "2025-09-11T16:52:17.725Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
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"url": "https://git.kernel.org/stable/c/e7a375453cca2b8a0d2fa1b82b913f3fed7c0507"
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{
"url": "https://git.kernel.org/stable/c/1cfa244f7198d325594e627574930b7b91df5bfe"
},
{
"url": "https://git.kernel.org/stable/c/ddebb2a7677673cf4438a04e1a48b8ed6b0c8e9a"
},
{
"url": "https://git.kernel.org/stable/c/56c5ef194f4509df63fc0f7a91ea5973ce479b1e"
},
{
"url": "https://git.kernel.org/stable/c/b41642c87716bbd09797b1e4ea7d904f06c39b7b"
}
],
"title": "rcu: Fix rcu_read_unlock() deadloop due to IRQ work",
"x_generator": {
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}
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"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2025-39744",
"datePublished": "2025-09-11T16:52:17.725Z",
"dateReserved": "2025-04-16T07:20:57.120Z",
"dateUpdated": "2025-09-11T16:52:17.725Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.1",
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}
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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