CVE-2026-90193 (GCVE-0-2026-90193)

Vulnerability from cvelistv5 – Published: 2026-09-17 16:07 – Updated: 2026-10-19 08:59
VLAI
Title
mailbox: qcom-cpucp: fix PREEMPT_RT self-deadlock in IRQ handler
Summary
In the Linux kernel, the following vulnerability has been resolved: mailbox: qcom-cpucp: fix PREEMPT_RT self-deadlock in IRQ handler qcom_cpucp_mbox_irq_fn() calls mbox_chan_received_data() while holding chan->lock. Under PREEMPT_RT, spin_lock_irqsave() is converted to an rt_spinlock (rtmutex-based), which tracks ownership and can sleep. The callback chain triggered by mbox_chan_received_data() eventually reaches mailbox_clear_channel() -> mbox_send_message() -> add_to_rbuf(), which attempts to re-acquire the same chan->lock. Since rtmutex detects the re-entrant lock attempt by the same owner, the thread blocks waiting for a lock it already holds, causing a permanent deadlock. This deadlock manifests as 'irq/N-apss_cpucp_mbox' stuck in D state with the following call trace: rt_spin_lock -> mbox_send_message -> mailbox_clear_channel -> scmi_rx_callback -> mbox_chan_received_data [<- held chan->lock here] Fix by saving chan->cl locally and clearing the HW interrupt register inside the lock, then invoking mbox_chan_received_data() after releasing the lock. This preserves the mutual exclusion for chan->cl access while avoiding the lock re-entrancy that causes the PREEMPT_RT deadlock.
Severity
No CVSS data available.
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 6643 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 0e2a9a03106cd5fa0dbc9047675e7645c55e2669 , < aa482273f32117c3adeba9b1cc945e0b5d33722d (git)
Affected: 0e2a9a03106cd5fa0dbc9047675e7645c55e2669 , < 8b8de6400c86937ed57d680d06d716e167b381de (git)
Affected: 0e2a9a03106cd5fa0dbc9047675e7645c55e2669 , < e40b3edeaf25cd09e9c88edb1ef99373ca37593b (git)
Affected: 0e2a9a03106cd5fa0dbc9047675e7645c55e2669 , < 3690aaa6d18f6775c3e7932fb8af8c5bf6a6b69c (git)
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Linux Linux Affected: 6.11
Unaffected: 0 , < 6.11 (semver)
Unaffected: 6.12.110 , ≤ 6.12.* (semver)
Unaffected: 6.18.52 , ≤ 6.18.* (semver)
Unaffected: 7.2.6 , ≤ 7.2.* (semver)
Unaffected: 7.3 , ≤ * (original_commit_for_fix)
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{
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          "product": "Linux",
          "programFiles": [
            "drivers/mailbox/qcom-cpucp-mbox.c"
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmailbox: qcom-cpucp: fix PREEMPT_RT self-deadlock in IRQ handler\n\nqcom_cpucp_mbox_irq_fn() calls mbox_chan_received_data() while holding\nchan-\u003elock. Under PREEMPT_RT, spin_lock_irqsave() is converted to an\nrt_spinlock (rtmutex-based), which tracks ownership and can sleep.\n\nThe callback chain triggered by mbox_chan_received_data() eventually\nreaches mailbox_clear_channel() -\u003e mbox_send_message() -\u003e add_to_rbuf(),\nwhich attempts to re-acquire the same chan-\u003elock. Since rtmutex detects\nthe re-entrant lock attempt by the same owner, the thread blocks waiting\nfor a lock it already holds, causing a permanent deadlock.\n\nThis deadlock manifests as \u0027irq/N-apss_cpucp_mbox\u0027 stuck in D state\nwith the following call trace:\n  rt_spin_lock -\u003e mbox_send_message -\u003e mailbox_clear_channel -\u003e\n  scmi_rx_callback -\u003e mbox_chan_received_data [\u003c- held chan-\u003elock here]\n\nFix by saving chan-\u003ecl locally and clearing the HW interrupt register\ninside the lock, then invoking mbox_chan_received_data() after releasing\nthe lock. This preserves the mutual exclusion for chan-\u003ecl access while\navoiding the lock re-entrancy that causes the PREEMPT_RT deadlock."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T08:59:29.783Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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        },
        {
          "url": "https://git.kernel.org/stable/c/3690aaa6d18f6775c3e7932fb8af8c5bf6a6b69c"
        }
      ],
      "title": "mailbox: qcom-cpucp: fix PREEMPT_RT self-deadlock in IRQ handler",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-90193",
    "datePublished": "2026-09-17T16:07:13.672Z",
    "dateReserved": "2026-09-11T19:38:34.792Z",
    "dateUpdated": "2026-10-19T08:59:29.783Z",
    "state": "PUBLISHED"
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      "title": "mailbox: qcom-cpucp: fix PREEMPT_RT self-deadlock in IRQ handler",
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      "version": "2"
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        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmailbox: qcom-cpucp: fix PREEMPT_RT self-deadlock in IRQ handler\n\nqcom_cpucp_mbox_irq_fn() calls mbox_chan_received_data() while holding\nchan-\u003elock. Under PREEMPT_RT, spin_lock_irqsave() is converted to an\nrt_spinlock (rtmutex-based), which tracks ownership and can sleep.\n\nThe callback chain triggered by mbox_chan_received_data() eventually\nreaches mailbox_clear_channel() -\u003e mbox_send_message() -\u003e add_to_rbuf(),\nwhich attempts to re-acquire the same chan-\u003elock. Since rtmutex detects\nthe re-entrant lock attempt by the same owner, the thread blocks waiting\nfor a lock it already holds, causing a permanent deadlock.\n\nThis deadlock manifests as \u0027irq/N-apss_cpucp_mbox\u0027 stuck in D state\nwith the following call trace:\n  rt_spin_lock -\u003e mbox_send_message -\u003e mailbox_clear_channel -\u003e\n  scmi_rx_callback -\u003e mbox_chan_received_data [\u003c- held chan-\u003elock here]\n\nFix by saving chan-\u003ecl locally and clearing the HW interrupt register\ninside the lock, then invoking mbox_chan_received_data() after releasing\nthe lock. This preserves the mutual exclusion for chan-\u003ecl access while\navoiding the lock re-entrancy that causes the PREEMPT_RT deadlock."
          }
        ],
        "id": "CVE-2026-90193",
        "lastModified": "2026-10-19T09:19:09.310",
        "metrics": {},
        "published": "2026-09-17T17:17:14.030",
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        "vulnStatus": "Received"
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      "cve": "CVE-2026-90193",
      "id": "CVE-2026-90193",
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      "product_status:known_not_affected": "203",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: mailbox: qcom-cpucp: fix PREEMPT_RT self-deadlock in IRQ handler",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-90193.json",
      "version": "3"
    }
  }
}



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