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CVE PROGRAM SOURCE RECORDUnscored

CVE-2026-89759

mm/kmemleak: avoid soft lockup when scanning task stacks

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Status
Published
Published
Updated
Assigning organization
Linux

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.

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

Linux Linux

Default version status: unaffected

  • c4b28963fd79457315783b3b0f21c01eb88cfdc1 to < 2567818c2776d0a820506c3612261d9e24af7164affected
  • c4b28963fd79457315783b3b0f21c01eb88cfdc1 to < f1cd6c4c35243377882c47236281d03ee3be6eebaffected
  • c4b28963fd79457315783b3b0f21c01eb88cfdc1 to < 9a1b12c06c192290b8479de48f66f1e75d89c4b7affected
  • c4b28963fd79457315783b3b0f21c01eb88cfdc1 to < 3fc8044251de21555fb02c365fa681bab8b0db55affected
  • c4b28963fd79457315783b3b0f21c01eb88cfdc1 to < 1838c704bcb4fd3556cf67513c6f97a39099e35caffected
  • c4b28963fd79457315783b3b0f21c01eb88cfdc1 to < 5d10d4e19e6daa487f0cd0ea6cba472325de92f9affected

Linux Linux

Default version status: affected

  • 5.10affected
  • 0 to < 5.10unaffected
  • 6.1.191 to ≤ 6.1.*unaffected
  • 6.6.160 to ≤ 6.6.*unaffected
  • 6.12.109 to ≤ 6.12.*unaffected
  • 6.18.50 to ≤ 6.18.*unaffected
  • 7.2.4 to ≤ 7.2.*unaffected
  • 7.3 to ≤ *unaffected

References