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CVE-2026-89759 (GCVE-0-2026-89759)

Vulnerability from cvelistv5 – Published: 2026-09-11 19:47 – Updated: 2026-09-11 19:47
VLAI
Title
mm/kmemleak: avoid soft lockup when scanning task stacks
Summary
In the Linux kernel, the following vulnerability has been resolved: mm/kmemleak: avoid soft lockup when scanning task stacks Patch series "mm/kmemleak: avoid soft lockup when scanning task", v3. kmemleak_scan() scans every task stack under one rcu_read_lock() with no reschedule point, which can trip the soft lockup watchdog on hosts with very many threads. That prints the following message, depending on the workload+host configuration: watchdog: BUG: soft lockup - CPU#35 stuck for 22s! [kmemleak:537] scan_block kmemleak_scan kmemleak_scan_thread kthread Patch 1 walks the tasks with find_ge_pid() so the scan reschedules between tasks Patches 2-3 let the scan loops stop early once a scan is interrupted. This patch (of 3): kmemleak_scan() walks every thread and scans its kernel stack under a single rcu_read_lock() with no reschedule point. On a host with very many threads -- amplified by KASAN/lockdep in debug builds -- this loop can hog a CPU long enough to trip the soft lockup watchdog: watchdog: BUG: soft lockup - CPU#35 stuck for 22s! [kmemleak:537] scan_block kmemleak_scan kmemleak_scan_thread kthread A cond_resched() cannot be added directly: the loop runs inside an RCU read-side critical section. Walk the tasks one PID at a time with find_ge_pid(), taking the RCU read lock only to look up and pin each task. The stack is then scanned with no lock held, so cond_resched() runs between tasks and the scan stops early on scan_should_stop(). This follows the next_tgid()/task_seq_get_next() iteration pattern and keeps each RCU critical section short.
Severity
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: c4b28963fd79457315783b3b0f21c01eb88cfdc1 , < 9a1b12c06c192290b8479de48f66f1e75d89c4b7 (git)
Affected: c4b28963fd79457315783b3b0f21c01eb88cfdc1 , < 3fc8044251de21555fb02c365fa681bab8b0db55 (git)
Affected: c4b28963fd79457315783b3b0f21c01eb88cfdc1 , < 1838c704bcb4fd3556cf67513c6f97a39099e35c (git)
Affected: c4b28963fd79457315783b3b0f21c01eb88cfdc1 , < 5d10d4e19e6daa487f0cd0ea6cba472325de92f9 (git)
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Linux Linux Affected: 5.10
Unaffected: 0 , < 5.10 (semver)
Unaffected: 6.12.109 , ≤ 6.12.* (semver)
Unaffected: 6.18.50 , ≤ 6.18.* (semver)
Unaffected: 7.2.4 , ≤ 7.2.* (semver)
Unaffected: 7.3-rc1 , ≤ * (original_commit_for_fix)
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "mm/kmemleak.c"
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          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm/kmemleak: avoid soft lockup when scanning task stacks\n\nPatch series \"mm/kmemleak: avoid soft lockup when scanning task\", v3.\n\nkmemleak_scan() scans every task stack under one rcu_read_lock() with no\nreschedule point, which can trip the soft lockup watchdog on hosts with\nvery many threads.\n\nThat prints the following message, depending on the workload+host\nconfiguration:\n\n      watchdog: BUG: soft lockup - CPU#35 stuck for 22s! [kmemleak:537]\n       scan_block\n       kmemleak_scan\n       kmemleak_scan_thread\n       kthread\n\nPatch 1 walks the tasks with find_ge_pid() so the scan reschedules between\ntasks\n\nPatches 2-3 let the scan loops stop early once a scan is interrupted.\n\n\nThis patch (of 3):\n\nkmemleak_scan() walks every thread and scans its kernel stack under a\nsingle rcu_read_lock() with no reschedule point.  On a host with very many\nthreads -- amplified by KASAN/lockdep in debug builds -- this loop can hog\na CPU long enough to trip the soft lockup watchdog:\n\n  watchdog: BUG: soft lockup - CPU#35 stuck for 22s! [kmemleak:537]\n   scan_block\n   kmemleak_scan\n   kmemleak_scan_thread\n   kthread\n\nA cond_resched() cannot be added directly: the loop runs inside an RCU\nread-side critical section.\n\nWalk the tasks one PID at a time with find_ge_pid(), taking the RCU read\nlock only to look up and pin each task.  The stack is then scanned with no\nlock held, so cond_resched() runs between tasks and the scan stops early\non scan_should_stop().  This follows the next_tgid()/task_seq_get_next()\niteration pattern and keeps each RCU critical section short."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-11T19:47:01.313Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
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        },
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          "url": "https://git.kernel.org/stable/c/3fc8044251de21555fb02c365fa681bab8b0db55"
        },
        {
          "url": "https://git.kernel.org/stable/c/1838c704bcb4fd3556cf67513c6f97a39099e35c"
        },
        {
          "url": "https://git.kernel.org/stable/c/5d10d4e19e6daa487f0cd0ea6cba472325de92f9"
        }
      ],
      "title": "mm/kmemleak: avoid soft lockup when scanning task stacks",
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  "cveMetadata": {
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-89759",
    "datePublished": "2026-09-11T19:47:01.313Z",
    "dateReserved": "2026-09-11T19:38:34.763Z",
    "dateUpdated": "2026-09-11T19:47:01.313Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-89759",
      "date": "2026-09-16",
      "epss": "0.00186",
      "percentile": "0.08459"
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      "cve": "CVE-2026-89759",
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      "initial_release_date": "2026-09-13T01:11:42.000Z",
      "product_status:known_not_affected": "1",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "mm/kmemleak: avoid soft lockup when scanning task stacks",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-89759.json",
      "version": "3"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-89759\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-09-11T20:20:06.997\",\"lastModified\":\"2026-09-11T20:20:06.997\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nmm/kmemleak: avoid soft lockup when scanning task stacks\\n\\nPatch series \\\"mm/kmemleak: avoid soft lockup when scanning task\\\", v3.\\n\\nkmemleak_scan() scans every task stack under one rcu_read_lock() with no\\nreschedule point, which can trip the soft lockup watchdog on hosts with\\nvery many threads.\\n\\nThat prints the following message, depending on the workload+host\\nconfiguration:\\n\\n      watchdog: BUG: soft lockup - CPU#35 stuck for 22s! [kmemleak:537]\\n       scan_block\\n       kmemleak_scan\\n       kmemleak_scan_thread\\n       kthread\\n\\nPatch 1 walks the tasks with find_ge_pid() so the scan reschedules between\\ntasks\\n\\nPatches 2-3 let the scan loops stop early once a scan is interrupted.\\n\\n\\nThis patch (of 3):\\n\\nkmemleak_scan() walks every thread and scans its kernel stack under a\\nsingle rcu_read_lock() with no reschedule point.  On a host with very many\\nthreads -- amplified by KASAN/lockdep in debug builds -- this loop can hog\\na CPU long enough to trip the soft lockup watchdog:\\n\\n  watchdog: BUG: soft lockup - CPU#35 stuck for 22s! [kmemleak:537]\\n   scan_block\\n   kmemleak_scan\\n   kmemleak_scan_thread\\n   kthread\\n\\nA cond_resched() cannot be added directly: the loop runs inside an RCU\\nread-side critical section.\\n\\nWalk the tasks one PID at a time with find_ge_pid(), taking the RCU read\\nlock only to look up and pin each task.  The stack is then scanned with no\\nlock held, so cond_resched() runs between tasks and the scan stops early\\non scan_should_stop().  This follows the next_tgid()/task_seq_get_next()\\niteration pattern and keeps each RCU critical section short.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"mm/kmemleak.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"c4b28963fd79457315783b3b0f21c01eb88cfdc1\",\"lessThan\":\"9a1b12c06c192290b8479de48f66f1e75d89c4b7\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"c4b28963fd79457315783b3b0f21c01eb88cfdc1\",\"lessThan\":\"3fc8044251de21555fb02c365fa681bab8b0db55\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"c4b28963fd79457315783b3b0f21c01eb88cfdc1\",\"lessThan\":\"1838c704bcb4fd3556cf67513c6f97a39099e35c\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"c4b28963fd79457315783b3b0f21c01eb88cfdc1\",\"lessThan\":\"5d10d4e19e6daa487f0cd0ea6cba472325de92f9\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"mm/kmemleak.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"5.10\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"5.10\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.109\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18.50\",\"lessThanOrEqual\":\"6.18.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.2.4\",\"lessThanOrEqual\":\"7.2.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.3-rc1\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/1838c704bcb4fd3556cf67513c6f97a39099e35c\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/3fc8044251de21555fb02c365fa681bab8b0db55\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/5d10d4e19e6daa487f0cd0ea6cba472325de92f9\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/9a1b12c06c192290b8479de48f66f1e75d89c4b7\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
    "redhat_vex": {
      "aggregate_severity": "Low",
      "current_release_date": "2026-09-15T11:49:06+00:00",
      "cve": "CVE-2026-89759",
      "id": "CVE-2026-89759",
      "initial_release_date": "2026-09-11T00:00:00+00:00",
      "product_status:known_affected": "248",
      "product_status:known_not_affected": "28",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: mm/kmemleak: avoid soft lockup when scanning task stacks",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89759.json",
      "version": "3"
    }
  }
}



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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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  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


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