{"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": "2026-01-13T15:29:14.483Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-01-13T15:29:14.483Z"}, "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-rc2", "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-rc2"}]}]}], "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."}], "id": "CVE-2025-68807", "lastModified": "2026-01-13T16:16:02.857", "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": "Received"}

{}

{}