CVE-2025-39744 (GCVE-0-2025-39744)

Vulnerability from cvelistv5 – Published: 2025-09-11 16:52 – Updated: 2026-01-02 15:32
VLAI?
Title
rcu: Fix rcu_read_unlock() deadloop due to IRQ work
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]
Severity ?
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 0864f057b050bc6dd68106b3185e02db5140012d , < e7a375453cca2b8a0d2fa1b82b913f3fed7c0507 (git)
Affected: 0864f057b050bc6dd68106b3185e02db5140012d , < 1cfa244f7198d325594e627574930b7b91df5bfe (git)
Affected: 0864f057b050bc6dd68106b3185e02db5140012d , < ddebb2a7677673cf4438a04e1a48b8ed6b0c8e9a (git)
Affected: 0864f057b050bc6dd68106b3185e02db5140012d , < 56c5ef194f4509df63fc0f7a91ea5973ce479b1e (git)
Affected: 0864f057b050bc6dd68106b3185e02db5140012d , < b41642c87716bbd09797b1e4ea7d904f06c39b7b (git)
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    Linux Linux Affected: 5.3
Unaffected: 0 , < 5.3 (semver)
Unaffected: 6.6.103 , ≤ 6.6.* (semver)
Unaffected: 6.12.43 , ≤ 6.12.* (semver)
Unaffected: 6.15.11 , ≤ 6.15.* (semver)
Unaffected: 6.16.2 , ≤ 6.16.* (semver)
Unaffected: 6.17 , ≤ * (original_commit_for_fix)
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{
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            "kernel/rcu/tree_plugin.h"
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          "vendor": "Linux",
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              "status": "unaffected",
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              "lessThanOrEqual": "6.16.*",
              "status": "unaffected",
              "version": "6.16.2",
              "versionType": "semver"
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              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.17",
              "versionType": "original_commit_for_fix"
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      "cpeApplicability": [
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          "nodes": [
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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": "2026-01-02T15:32:01.715Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
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          "url": "https://git.kernel.org/stable/c/e7a375453cca2b8a0d2fa1b82b913f3fed7c0507"
        },
        {
          "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",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2025-39744",
    "datePublished": "2025-09-11T16:52:17.725Z",
    "dateReserved": "2025-04-16T07:20:57.120Z",
    "dateUpdated": "2026-01-02T15:32:01.715Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
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