{"id":"CVE-2026-89759","title":"mm/kmemleak: avoid soft lockup when scanning task stacks","summary":"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 …","severity":"medium","cvss":5.5,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","cvssSource":"vendor","cwe":["CWE-1050"],"vendor":"Linux","product":"Linux","affected":["Linux >= c4b28963fd79457315783b3b0f21c01eb88cfdc1 < f1cd6c4c35243377882c47236281d03ee3be6eeb","Linux >= c4b28963fd79457315783b3b0f21c01eb88cfdc1 < 9a1b12c06c192290b8479de48f66f1e75d89c4b7","Linux >= c4b28963fd79457315783b3b0f21c01eb88cfdc1 < 3fc8044251de21555fb02c365fa681bab8b0db55","Linux >= c4b28963fd79457315783b3b0f21c01eb88cfdc1 < 1838c704bcb4fd3556cf67513c6f97a39099e35c","Linux >= c4b28963fd79457315783b3b0f21c01eb88cfdc1 < 5d10d4e19e6daa487f0cd0ea6cba472325de92f9","Linux 5.10"],"published":"2026-09-11","updated":"2026-10-21","sourceUpdated":"2026-10-21T12:48:36.907Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-89759","references":[{"url":"https://git.kernel.org/stable/c/f1cd6c4c35243377882c47236281d03ee3be6eeb"},{"url":"https://git.kernel.org/stable/c/9a1b12c06c192290b8479de48f66f1e75d89c4b7"},{"url":"https://git.kernel.org/stable/c/3fc8044251de21555fb02c365fa681bab8b0db55"},{"url":"https://git.kernel.org/stable/c/1838c704bcb4fd3556cf67513c6f97a39099e35c"},{"url":"https://git.kernel.org/stable/c/5d10d4e19e6daa487f0cd0ea6cba472325de92f9"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89759.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-89759"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2532495"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-89759"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89759"},{"url":"https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89759.mbox"}],"tags":["cve.org","csaf","vex","red-hat"],"epss":0.00192,"epssPercentile":0.08796,"ingestedAt":"2026-09-14T11:11:19.884Z","slug":"CVE-2026-89759","body":"## Overview\n\nIn 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.\n\n## Affected\n\n- `Linux >= c4b28963fd79457315783b3b0f21c01eb88cfdc1 < f1cd6c4c35243377882c47236281d03ee3be6eeb`\n- `Linux >= c4b28963fd79457315783b3b0f21c01eb88cfdc1 < 9a1b12c06c192290b8479de48f66f1e75d89c4b7`\n- `Linux >= c4b28963fd79457315783b3b0f21c01eb88cfdc1 < 3fc8044251de21555fb02c365fa681bab8b0db55`\n- `Linux >= c4b28963fd79457315783b3b0f21c01eb88cfdc1 < 1838c704bcb4fd3556cf67513c6f97a39099e35c`\n- `Linux >= c4b28963fd79457315783b3b0f21c01eb88cfdc1 < 5d10d4e19e6daa487f0cd0ea6cba472325de92f9`\n- `Linux 5.10`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Vendor advisories\n\n- **Red Hat VEX** · Low · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, … · updated 2026-09-15 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89759.json)","depth":"sunlit","depthScore":30,"depthScoreParts":{"impact":30.3,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[{"seq":203896,"id":"CVE-2026-89759","ts":1789490213837,"field":"cvss","old":null,"new":"5.5"},{"seq":203895,"id":"CVE-2026-89759","ts":1789490213837,"field":"severity","old":"none","new":"medium"},{"seq":147113,"id":"CVE-2026-89759","ts":1789270195224,"field":"cvss","old":null,"new":"4.7"},{"seq":147112,"id":"CVE-2026-89759","ts":1789270195224,"field":"severity","old":"none","new":"medium"},{"seq":108862,"id":"CVE-2026-89759","ts":1789183729301,"field":"cvss","old":null,"new":"4.7"},{"seq":108861,"id":"CVE-2026-89759","ts":1789183729301,"field":"severity","old":"none","new":"medium"}]}