FKIE_CVE-2026-80916

Vulnerability from fkie_nvd - Published: 2026-09-09 17:17 - Updated: 2026-10-19 09:17
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved: kcov: fix data corruption and race conditions on PREEMPT_RT syzbot is reporting KCOV state corruption on PREEMPT_RT kernels, for the temporary storage used for saving/restoring remote KCOV state is currently allocated as the per-CPU area. On PREEMPT_RT kernels, softirq handlers run as preemptible task threads (e.g., ksoftirqd). If a softirq context preempts a task running a remote KCOV session, it safely saves the task's state into the per-CPU area. However, if that softirq thread is subsequently preempted by a higher- priority softirq thread on the same CPU, the second softirq will overwrite the same per-CPU area, permanently destroying the original task's KCOV state. Fix this data corruption by moving the temporary storage from the per-CPU area to the per-thread area. Since each softirq thread now owns its own task context, nested softirq preemption no longer causes data overwrites. Note that while the temporary storage is now on a per-thread basis, the per-CPU kcov_percpu_data.lock must be retained, for we need to ensure that kcov_remote_start() and kcov_remote_stop() operate atomically without racing against asynchronous interrupts that manipulate the current task's KCOV state. It is likely that GFP_KERNEL allocation by vmalloc_node() in kcov_init() has already called panic() before returning NULL, for there will be no OOM-killable userspace processes when __init function of built-in module runs. But this patch also fixes crashing the kernel when vmalloc_node() in kcov_init() returned NULL, for kcov_init() left per-CPU irq_area == NULL but kcov_remote_start() depends on per-CPU irq_area != NULL, resulting in (1) doing vmalloc() in kcov_remote_start() despite !in_task() context (2) out-of-array-bounds access if (1) succeeded but kcov->remote_size < CONFIG_KCOV_IRQ_AREA_SIZE (3) always leak memory allocated by (1), eventually killing all OOM-killable userspace processes problems.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/18799e858b407bf355383c9dd6c06477aa437134
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/22670d1552fe155822b2abf91f920925f7d067b4
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/2eed77fdcb0cc48e8eccb2bcd4b7f2c6d650e84c
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/5dc59fc959b2b5742985d7ef24bccd1868217dc2
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/8ed3ddf23d39bf5338406bd9f8863d44748cf6ce
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/a2fb8222cde23b0001812ed3acb7c0ea36dd94e2
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/e11f5b48c82703242a3be7a7ae4b4940b4cb4610
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/ef7048d8a614c5f5a9b20513a5428101a744514e
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/f8c9a3ec36b4ee3d4701b9be08f40e7bfbf89761
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "include/linux/sched.h",
            "kernel/kcov.c",
            "lib/Kconfig.debug"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "ef7048d8a614c5f5a9b20513a5428101a744514e",
              "status": "affected",
              "version": "5ff3b30ab57da82d8db4f14662a2858cabfbc2c0",
              "versionType": "git"
            },
            {
              "lessThan": "8ed3ddf23d39bf5338406bd9f8863d44748cf6ce",
              "status": "affected",
              "version": "5ff3b30ab57da82d8db4f14662a2858cabfbc2c0",
              "versionType": "git"
            },
            {
              "lessThan": "5dc59fc959b2b5742985d7ef24bccd1868217dc2",
              "status": "affected",
              "version": "5ff3b30ab57da82d8db4f14662a2858cabfbc2c0",
              "versionType": "git"
            },
            {
              "lessThan": "a2fb8222cde23b0001812ed3acb7c0ea36dd94e2",
              "status": "affected",
              "version": "5ff3b30ab57da82d8db4f14662a2858cabfbc2c0",
              "versionType": "git"
            },
            {
              "lessThan": "18799e858b407bf355383c9dd6c06477aa437134",
              "status": "affected",
              "version": "5ff3b30ab57da82d8db4f14662a2858cabfbc2c0",
              "versionType": "git"
            },
            {
              "lessThan": "e11f5b48c82703242a3be7a7ae4b4940b4cb4610",
              "status": "affected",
              "version": "5ff3b30ab57da82d8db4f14662a2858cabfbc2c0",
              "versionType": "git"
            },
            {
              "lessThan": "22670d1552fe155822b2abf91f920925f7d067b4",
              "status": "affected",
              "version": "5ff3b30ab57da82d8db4f14662a2858cabfbc2c0",
              "versionType": "git"
            },
            {
              "lessThan": "f8c9a3ec36b4ee3d4701b9be08f40e7bfbf89761",
              "status": "affected",
              "version": "5ff3b30ab57da82d8db4f14662a2858cabfbc2c0",
              "versionType": "git"
            },
            {
              "lessThan": "2eed77fdcb0cc48e8eccb2bcd4b7f2c6d650e84c",
              "status": "affected",
              "version": "5ff3b30ab57da82d8db4f14662a2858cabfbc2c0",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "include/linux/sched.h",
            "kernel/kcov.c",
            "lib/Kconfig.debug"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.8"
            },
            {
              "lessThan": "5.8",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.10.*",
              "status": "unaffected",
              "version": "5.10.269",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.220",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.185",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.154",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.106",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.47",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.11",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.1",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nkcov: fix data corruption and race conditions on PREEMPT_RT\n\nsyzbot is reporting KCOV state corruption on PREEMPT_RT kernels, for the\ntemporary storage used for saving/restoring remote KCOV state is currently\nallocated as the per-CPU area.\n\nOn PREEMPT_RT kernels, softirq handlers run as preemptible task threads\n(e.g., ksoftirqd). If a softirq context preempts a task running a remote\nKCOV session, it safely saves the task\u0027s state into the per-CPU area.\nHowever, if that softirq thread is subsequently preempted by a higher-\npriority softirq thread on the same CPU, the second softirq will overwrite\nthe same per-CPU area, permanently destroying the original task\u0027s KCOV\nstate.\n\nFix this data corruption by moving the temporary storage from the per-CPU\narea to the per-thread area. Since each softirq thread now owns its own\ntask context, nested softirq preemption no longer causes data overwrites.\n\nNote that while the temporary storage is now on a per-thread basis, the\nper-CPU kcov_percpu_data.lock must be retained, for we need to ensure that\nkcov_remote_start() and kcov_remote_stop() operate atomically without\nracing against asynchronous interrupts that manipulate the current task\u0027s\nKCOV state.\n\nIt is likely that GFP_KERNEL allocation by vmalloc_node() in kcov_init()\nhas already called panic() before returning NULL, for there will be no\nOOM-killable userspace processes when __init function of built-in module\nruns. But this patch also fixes crashing the kernel when vmalloc_node()\nin kcov_init() returned NULL, for kcov_init() left per-CPU irq_area == NULL\nbut kcov_remote_start() depends on per-CPU irq_area != NULL, resulting in\n\n  (1) doing vmalloc() in kcov_remote_start() despite !in_task() context\n\n  (2) out-of-array-bounds access if (1) succeeded but\n      kcov-\u003eremote_size \u003c CONFIG_KCOV_IRQ_AREA_SIZE\n\n  (3) always leak memory allocated by (1), eventually killing all\n      OOM-killable userspace processes\n\nproblems."
    }
  ],
  "id": "CVE-2026-80916",
  "lastModified": "2026-10-19T09:17:22.417",
  "metrics": {},
  "published": "2026-09-09T17:17:46.513",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/18799e858b407bf355383c9dd6c06477aa437134"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/22670d1552fe155822b2abf91f920925f7d067b4"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/2eed77fdcb0cc48e8eccb2bcd4b7f2c6d650e84c"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/5dc59fc959b2b5742985d7ef24bccd1868217dc2"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/8ed3ddf23d39bf5338406bd9f8863d44748cf6ce"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/a2fb8222cde23b0001812ed3acb7c0ea36dd94e2"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/e11f5b48c82703242a3be7a7ae4b4940b4cb4610"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/ef7048d8a614c5f5a9b20513a5428101a744514e"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/f8c9a3ec36b4ee3d4701b9be08f40e7bfbf89761"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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