CVE-2026-89759
Full vulnerability record from the local CVENow database.
Description
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.
View original CVE JSON
{
"id": "CVE-2026-89759",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"published": "2026-09-11T20:20:06.997",
"lastModified": "2026-10-30T13:20:28.370",
"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": "2567818c2776d0a820506c3612261d9e24af7164",
"versionType": "git",
"status": "affected"
},
{
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"lessThan": "f1cd6c4c35243377882c47236281d03ee3be6eeb",
"versionType": "git",
"status": "affected"
},
{
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"lessThan": "9a1b12c06c192290b8479de48f66f1e75d89c4b7",
"versionType": "git",
"status": "affected"
},
{
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"status": "affected"
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{
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"versionType": "git",
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{
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"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": "6.1.191",
"lessThanOrEqual": "6.1.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.6.160",
"lessThanOrEqual": "6.6.*",
"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",
"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/2567818c2776d0a820506c3612261d9e24af7164",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/3fc8044251de21555fb02c365fa681bab8b0db55",
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{
"url": "https://git.kernel.org/stable/c/5d10d4e19e6daa487f0cd0ea6cba472325de92f9",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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{
"url": "https://git.kernel.org/stable/c/9a1b12c06c192290b8479de48f66f1e75d89c4b7",
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{
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"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
]
}