CVE-2025-39737
Full vulnerability record from the local CVENow database.
Description
In the Linux kernel, the following vulnerability has been resolved: mm/kmemleak: avoid soft lockup in __kmemleak_do_cleanup() A soft lockup warning was observed on a relative small system x86-64 system with 16 GB of memory when running a debug kernel with kmemleak enabled. watchdog: BUG: soft lockup - CPU#8 stuck for 33s! [kworker/8:1:134] The test system was running a workload with hot unplug happening in parallel. Then kemleak decided to disable itself due to its inability to allocate more kmemleak objects. The debug kernel has its CONFIG_DEBUG_KMEMLEAK_MEM_POOL_SIZE set to 40,000. The soft lockup happened in kmemleak_do_cleanup() when the existing kmemleak objects were being removed and deleted one-by-one in a loop via a workqueue. In this particular case, there are at least 40,000 objects that need to be processed and given the slowness of a debug kernel and the fact that a raw_spinlock has to be acquired and released in __delete_object(), it could take a while to properly handle all these objects. As kmemleak has been disabled in this case, the object removal and deletion process can be further optimized as locking isn't really needed. However, it is probably not worth the effort to optimize for such an edge case that should rarely happen. So the simple solution is to call cond_resched() at periodic interval in the iteration loop to avoid soft lockup.
Severity
MEDIUM
CVSS score
5.5
(v3.1)
Vulnerability status
Modified
Source identifier
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Published
2025-09-11 17:15:35.173000
Last modified
2026-10-19 21:10:00.160000
View original CVE JSON
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"published": "2025-09-11T17:15:35.173",
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm/kmemleak: avoid soft lockup in __kmemleak_do_cleanup()\n\nA soft lockup warning was observed on a relative small system x86-64\nsystem with 16 GB of memory when running a debug kernel with kmemleak\nenabled.\n\n watchdog: BUG: soft lockup - CPU#8 stuck for 33s! [kworker/8:1:134]\n\nThe test system was running a workload with hot unplug happening in\nparallel. Then kemleak decided to disable itself due to its inability to\nallocate more kmemleak objects. The debug kernel has its\nCONFIG_DEBUG_KMEMLEAK_MEM_POOL_SIZE set to 40,000.\n\nThe soft lockup happened in kmemleak_do_cleanup() when the existing\nkmemleak objects were being removed and deleted one-by-one in a loop via a\nworkqueue. In this particular case, there are at least 40,000 objects\nthat need to be processed and given the slowness of a debug kernel and the\nfact that a raw_spinlock has to be acquired and released in\n__delete_object(), it could take a while to properly handle all these\nobjects.\n\nAs kmemleak has been disabled in this case, the object removal and\ndeletion process can be further optimized as locking isn't really needed. \nHowever, it is probably not worth the effort to optimize for such an edge\ncase that should rarely happen. So the simple solution is to call\ncond_resched() at periodic interval in the iteration loop to avoid soft\nlockup."
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"value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nmm/kmemleak: evitar un soft lockup en __kmemleak_do_cleanup()\n\nSe observó una advertencia de soft lockup en un sistema x86-64 relativamente pequeño con 16 GB de memoria al ejecutar un kernel de depuración con kmemleak habilitado.\n\n watchdog: BUG: soft lockup - CPU#8 atascada durante 33s! [kworker/8:1:134]\n\nEl sistema de prueba estaba ejecutando una carga de trabajo con hot unplug ocurriendo en paralelo. Entonces kmemleak decidió deshabilitarse debido a su incapacidad para asignar más objetos kmemleak. El kernel de depuración tiene su CONFIG_DEBUG_KMEMLEAK_MEM_POOL_SIZE configurado en 40.000.\n\nEl soft lockup ocurrió en kmemleak_do_cleanup() cuando los objetos kmemleak existentes estaban siendo eliminados y borrados uno por uno en un bucle a través de una workqueue. En este caso particular, hay al menos 40.000 objetos que necesitan ser procesados y, dada la lentitud de un kernel de depuración y el hecho de que un raw_spinlock tiene que ser adquirido y liberado en __delete_object(), podría llevar un tiempo manejar correctamente todos estos objetos.\n\nComo kmemleak ha sido deshabilitado en este caso, el proceso de eliminación y borrado de objetos puede ser optimizado aún más ya que el bloqueo no es realmente necesario. Sin embargo, probablemente no vale la pena el esfuerzo de optimizar para un caso tan extremo que rara vez debería ocurrir. Así que la solución simple es llamar a cond_resched() a intervalos periódicos en el bucle de iteración para evitar un soft lockup."
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