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

Vulnerability from cvelistv5 – Published: 2025-09-11 16:52 – Updated: 2026-05-11 21:35
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
7.1 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 7061 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
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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            "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]"
          },
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            "lang": "es",
            "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nrcu: Correcci\u00f3n del bucle muerto de rcu_read_unlock() debido al trabajo IRQ\n\nDurante rcu_read_unlock_special(), si esto ocurre durante irq_exit(), podemos bloquearnos si se emite un IPI. Esto se debe a que el propio IPI desencadena la ruta de irq_exit() causando un bloqueo recursivo.\n\nEsto es precisamente lo que Xiongfeng encontr\u00f3 al invocar un programa BPF en el punto de rastreo trace_tick_stop(). Como se muestra en el rastreo a continuaci\u00f3n. Se corrige gestionando el estado de irq_work correctamente.\n\nirq_exit()\n  __irq_exit_rcu()\n    /* in_hardirq() devuelve falso despu\u00e9s de esto */\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()  /* un programa bpf est\u00e1 enganchado a este punto de rastreo */\n\t\t   __bpf_trace_tick_stop()\n\t\t      bpf_trace_run2()\n\t\t\t    rcu_read_unlock_special()\n                              /* enviar\u00e1 un IPI a s\u00ed mismo */\n\t\t\t      irq_work_queue_on(\u0026rdp-\u003edefer_qs_iw, rdp-\u003ecpu);\n\nUn reproductor simple tambi\u00e9n se puede obtener haciendo lo siguiente en tick_irq_exit(). Se colgar\u00e1 al arrancar sin el parche:\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: Aplicar la correcci\u00f3n sugerida por Frederic para PREEMPT_RT]"
          }
        ],
        "id": "CVE-2025-39744",
        "lastModified": "2026-10-19T21:10:00.160",
        "metrics": {
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                "attackVector": "LOCAL",
                "availabilityImpact": "HIGH",
                "baseScore": 7.1,
                "baseSeverity": "HIGH",
                "confidentialityImpact": "HIGH",
                "integrityImpact": "NONE",
                "privilegesRequired": "LOW",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H",
                "version": "3.1"
              },
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              "impactScore": 5.2,
              "source": "nvd@nist.gov",
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            }
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        "published": "2025-09-11T17:15:37.600",
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        "vulnStatus": "Analyzed",
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                "lang": "en",
                "value": "CWE-125"
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            "source": "nvd@nist.gov",
            "type": "Primary"
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    "redhat_vex": {
      "aggregate_severity": "None",
      "current_release_date": "2026-06-30T10:23:50+00:00",
      "cve": "CVE-2025-39744",
      "id": "CVE-2025-39744",
      "initial_release_date": "2025-09-11T00:00:00+00:00",
      "product_status:known_not_affected": "274",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: rcu: Fix rcu_read_unlock() deadloop due to IRQ work",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-39744.json",
      "version": "3"
    }
  }
}



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    Related by attack behaviour

    Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.