{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2025-68807", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2025-12-24T10:30:51.045Z", "datePublished": "2026-01-13T15:29:14.483Z", "dateUpdated": "2026-02-09T08:33:56.250Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-02-09T08:33:56.250Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nblock: fix race between wbt_enable_default and IO submission\n\nWhen wbt_enable_default() is moved out of queue freezing in elevator_change(),\nit can cause the wbt inflight counter to become negative (-1), leading to hung\ntasks in the writeback path. Tasks get stuck in wbt_wait() because the counter\nis in an inconsistent state.\n\nThe issue occurs because wbt_enable_default() could race with IO submission,\nallowing the counter to be decremented before proper initialization. This manifests\nas:\n\n rq_wait[0]:\n inflight: -1\n has_waiters: True\n\nrwb_enabled() checks the state, which can be updated exactly between wbt_wait()\n(rq_qos_throttle()) and wbt_track()(rq_qos_track()), then the inflight counter\nwill become negative.\n\nAnd results in hung task warnings like:\n task:kworker/u24:39 state:D stack:0 pid:14767\n Call Trace:\n rq_qos_wait+0xb4/0x150\n wbt_wait+0xa9/0x100\n __rq_qos_throttle+0x24/0x40\n blk_mq_submit_bio+0x672/0x7b0\n ...\n\nFix this by:\n\n1. Splitting wbt_enable_default() into:\n - __wbt_enable_default(): Returns true if wbt_init() should be called\n - wbt_enable_default(): Wrapper for existing callers (no init)\n - wbt_init_enable_default(): New function that checks and inits WBT\n\n2. Using wbt_init_enable_default() in blk_register_queue() to ensure\n proper initialization during queue registration\n\n3. Move wbt_init() out of wbt_enable_default() which is only for enabling\n disabled wbt from bfq and iocost, and wbt_init() isn't needed. Then the\n original lock warning can be avoided.\n\n4. Removing the ELEVATOR_FLAG_ENABLE_WBT_ON_EXIT flag and its handling\n code since it's no longer needed\n\nThis ensures WBT is properly initialized before any IO can be submitted,\npreventing the counter from going negative."}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["block/bfq-iosched.c", "block/blk-sysfs.c", "block/blk-wbt.c", "block/blk-wbt.h", "block/elevator.c", "block/elevator.h"], "versions": [{"version": "78c271344b6f64ce24c845e54903e09928cf2061", "lessThan": "f55201fb3becff6a903fd29f4d1147cc7e91eb0c", "status": "affected", "versionType": "git"}, {"version": "78c271344b6f64ce24c845e54903e09928cf2061", "lessThan": "9869d3a6fed381f3b98404e26e1afc75d680cbf9", "status": "affected", "versionType": "git"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["block/bfq-iosched.c", "block/blk-sysfs.c", "block/blk-wbt.c", "block/blk-wbt.h", "block/elevator.c", "block/elevator.h"], "versions": [{"version": "6.16", "status": "affected"}, {"version": "0", "lessThan": "6.16", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.3", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.19", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix"}]}], "cpeApplicability": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.16", "versionEndExcluding": "6.18.3"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.16", "versionEndExcluding": "6.19"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/f55201fb3becff6a903fd29f4d1147cc7e91eb0c"}, {"url": "https://git.kernel.org/stable/c/9869d3a6fed381f3b98404e26e1afc75d680cbf9"}], "title": "block: fix race between wbt_enable_default and IO submission", "x_generator": {"engine": "bippy-1.2.0"}}}}

{}

{"cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nblock: fix race between wbt_enable_default and IO submission\n\nWhen wbt_enable_default() is moved out of queue freezing in elevator_change(),\nit can cause the wbt inflight counter to become negative (-1), leading to hung\ntasks in the writeback path. Tasks get stuck in wbt_wait() because the counter\nis in an inconsistent state.\n\nThe issue occurs because wbt_enable_default() could race with IO submission,\nallowing the counter to be decremented before proper initialization. This manifests\nas:\n\n rq_wait[0]:\n inflight: -1\n has_waiters: True\n\nrwb_enabled() checks the state, which can be updated exactly between wbt_wait()\n(rq_qos_throttle()) and wbt_track()(rq_qos_track()), then the inflight counter\nwill become negative.\n\nAnd results in hung task warnings like:\n task:kworker/u24:39 state:D stack:0 pid:14767\n Call Trace:\n rq_qos_wait+0xb4/0x150\n wbt_wait+0xa9/0x100\n __rq_qos_throttle+0x24/0x40\n blk_mq_submit_bio+0x672/0x7b0\n ...\n\nFix this by:\n\n1. Splitting wbt_enable_default() into:\n - __wbt_enable_default(): Returns true if wbt_init() should be called\n - wbt_enable_default(): Wrapper for existing callers (no init)\n - wbt_init_enable_default(): New function that checks and inits WBT\n\n2. Using wbt_init_enable_default() in blk_register_queue() to ensure\n proper initialization during queue registration\n\n3. Move wbt_init() out of wbt_enable_default() which is only for enabling\n disabled wbt from bfq and iocost, and wbt_init() isn't needed. Then the\n original lock warning can be avoided.\n\n4. Removing the ELEVATOR_FLAG_ENABLE_WBT_ON_EXIT flag and its handling\n code since it's no longer needed\n\nThis ensures WBT is properly initialized before any IO can be submitted,\npreventing the counter from going negative."}, {"lang": "es", "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nblock: corrige la condici\u00f3n de carrera entre wbt_enable_default y el env\u00edo de E/S\n\nCuando wbt_enable_default() se mueve fuera de la congelaci\u00f3n de la cola en elevator_change(), puede hacer que el contador inflight de wbt se vuelva negativo (-1), lo que lleva a tareas colgadas en la ruta de writeback. Las tareas se quedan atascadas en wbt_wait() porque el contador est\u00e1 en un estado inconsistente.\n\nEl problema ocurre porque wbt_enable_default() podr\u00eda competir con el env\u00edo de E/S, permitiendo que el contador se decremente antes de la inicializaci\u00f3n adecuada. Esto se manifiesta como:\n\n rq_wait[0]:\n inflight: -1\n has_waiters: True\n\nrwb_enabled() verifica el estado, que puede actualizarse exactamente entre wbt_wait() (rq_qos_throttle()) y wbt_track()(rq_qos_track()), entonces el contador inflight se volver\u00e1 negativo.\n\nY resulta en advertencias de tareas colgadas como:\n task:kworker/u24:39 state:D stack:0 pid:14767\n Call Trace:\n rq_qos_wait+0xb4/0x150\n wbt_wait+0xa9/0x100\n __rq_qos_throttle+0x24/0x40\n blk_mq_submit_bio+0x672/0x7b0\n ...\n\nEsto se soluciona mediante:\n\n1. Dividiendo wbt_enable_default() en:\n - __wbt_enable_default(): Devuelve verdadero si se debe llamar a wbt_init()\n - wbt_enable_default(): Envoltorio para las funciones que ya lo llaman (sin inicializaci\u00f3n)\n - wbt_init_enable_default(): Nueva funci\u00f3n que verifica e inicializa WBT\n\n2. Usando wbt_init_enable_default() en blk_register_queue() para asegurar una inicializaci\u00f3n adecuada durante el registro de la cola\n\n3. Moviendo wbt_init() fuera de wbt_enable_default(), que es solo para habilitar wbt deshabilitado de bfq e iocost, y wbt_init() no es necesario. As\u00ed se puede evitar la advertencia de bloqueo original.\n\n4. Eliminando la bandera ELEVATOR_FLAG_ENABLE_WBT_ON_EXIT y su c\u00f3digo de manejo, ya que ya no es necesario\n\nEsto asegura que WBT se inicialice correctamente antes de que se pueda enviar cualquier E/S, evitando que el contador se vuelva negativo."}], "id": "CVE-2025-68807", "lastModified": "2026-04-15T00:35:42.020", "metrics": {}, "published": "2026-01-13T16:16:02.857", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/9869d3a6fed381f3b98404e26e1afc75d680cbf9"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/f55201fb3becff6a903fd29f4d1147cc7e91eb0c"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Deferred"}

{"bugzilla": {"description": "kernel: block: fix race between wbt_enable_default and IO submission", "id": "2429069", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2429069"}, "csaw": false, "cvss3": {"cvss3_base_score": "5.5", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "status": "draft"}, "details": ["In the Linux kernel, the following vulnerability has been resolved:\nblock: fix race between wbt_enable_default and IO submission\nWhen wbt_enable_default() is moved out of queue freezing in elevator_change(),\nit can cause the wbt inflight counter to become negative (-1), leading to hung\ntasks in the writeback path. Tasks get stuck in wbt_wait() because the counter\nis in an inconsistent state.\nThe issue occurs because wbt_enable_default() could race with IO submission,\nallowing the counter to be decremented before proper initialization. This manifests\nas:\nrq_wait[0]:\ninflight: -1\nhas_waiters: True\nrwb_enabled() checks the state, which can be updated exactly between wbt_wait()\n(rq_qos_throttle()) and wbt_track()(rq_qos_track()), then the inflight counter\nwill become negative.\nAnd results in hung task warnings like:\ntask:kworker/u24:39 state:D stack:0 pid:14767\nCall Trace:\nrq_qos_wait+0xb4/0x150\nwbt_wait+0xa9/0x100\n__rq_qos_throttle+0x24/0x40\nblk_mq_submit_bio+0x672/0x7b0\n...\nFix this by:\n1. Splitting wbt_enable_default() into:\n- __wbt_enable_default(): Returns true if wbt_init() should be called\n- wbt_enable_default(): Wrapper for existing callers (no init)\n- wbt_init_enable_default(): New function that checks and inits WBT\n2. Using wbt_init_enable_default() in blk_register_queue() to ensure\nproper initialization during queue registration\n3. Move wbt_init() out of wbt_enable_default() which is only for enabling\ndisabled wbt from bfq and iocost, and wbt_init() isn't needed. Then the\noriginal lock warning can be avoided.\n4. Removing the ELEVATOR_FLAG_ENABLE_WBT_ON_EXIT flag and its handling\ncode since it's no longer needed\nThis ensures WBT is properly initialized before any IO can be submitted,\npreventing the counter from going negative."], "name": "CVE-2025-68807", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Fix deferred", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Fix deferred", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Fix deferred", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2026-01-13T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2025-68807\nhttps://nvd.nist.gov/vuln/detail/CVE-2025-68807\nhttps://lore.kernel.org/linux-cve-announce/2026011310-CVE-2025-68807-0fd6@gregkh/T"], "threat_severity": "Low"}

{}