CVE-2025-21664

{"id": "CVE-2025-21664", "cveTags": [], "metrics": {"cvssMetricV31": [{"type": "Primary", "source": "nvd@nist.gov", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 5.5, "attackVector": "LOCAL", "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "LOW", "confidentialityImpact": "NONE"}, "impactScore": 3.6, "exploitabilityScore": 1.8}]}, "published": "2025-01-21T13:15:10.053", "references": [{"url": "https://git.kernel.org/stable/c/12771050b6d059eea096993bf2001da9da9fddff", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/6b305e98de0d225ccebfb225730a9f560d28ecb0", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/802666a40c71a23542c43a3f87e3a2d0f4e8fe45", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/80f130bfad1dab93b95683fc39b87235682b8f72", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/cbd0d5ecfa390ac29c5380200147d09c381b2ac6", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/cd30a3960433ec2db94b3689752fa3c5df44d649", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/ec037fe8c0d0f6140e3d8a49c7b29cb5582160b8", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://lists.debian.org/debian-lts-announce/2025/03/msg00001.html", "source": "af854a3a-2127-422b-91ae-364da2661108"}, {"url": "https://lists.debian.org/debian-lts-announce/2025/03/msg00002.html", "source": "af854a3a-2127-422b-91ae-364da2661108"}], "vulnStatus": "Modified", "weaknesses": [{"type": "Primary", "source": "nvd@nist.gov", "description": [{"lang": "en", "value": "NVD-CWE-noinfo"}]}], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ndm thin: make get_first_thin use rcu-safe list first function\n\nThe documentation in rculist.h explains the absence of list_empty_rcu()\nand cautions programmers against relying on a list_empty() ->\nlist_first() sequence in RCU safe code. This is because each of these\nfunctions performs its own READ_ONCE() of the list head. This can lead\nto a situation where the list_empty() sees a valid list entry, but the\nsubsequent list_first() sees a different view of list head state after a\nmodification.\n\nIn the case of dm-thin, this author had a production box crash from a GP\nfault in the process_deferred_bios path. This function saw a valid list\nhead in get_first_thin() but when it subsequently dereferenced that and\nturned it into a thin_c, it got the inside of the struct pool, since the\nlist was now empty and referring to itself. The kernel on which this\noccurred printed both a warning about a refcount_t being saturated, and\na UBSAN error for an out-of-bounds cpuid access in the queued spinlock,\nprior to the fault itself. When the resulting kdump was examined, it\nwas possible to see another thread patiently waiting in thin_dtr's\nsynchronize_rcu.\n\nThe thin_dtr call managed to pull the thin_c out of the active thins\nlist (and have it be the last entry in the active_thins list) at just\nthe wrong moment which lead to this crash.\n\nFortunately, the fix here is straight forward. Switch get_first_thin()\nfunction to use list_first_or_null_rcu() which performs just a single\nREAD_ONCE() and returns NULL if the list is already empty.\n\nThis was run against the devicemapper test suite's thin-provisioning\nsuites for delete and suspend and no regressions were observed."}, {"lang": "es", "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: dm thin: hacer que get_first_thin use la funci\u00f3n list first de rcu-safe La documentaci\u00f3n en rculist.h explica la ausencia de list_empty_rcu() y advierte a los programadores que no conf\u00eden en una secuencia list_empty() -> list_first() en el c\u00f3digo seguro de RCU. Esto se debe a que cada una de estas funciones realiza su propio READ_ONCE() del encabezado de la lista. Esto puede llevar a una situaci\u00f3n en la que list_empty() ve una entrada de lista v\u00e1lida, pero el list_first() posterior ve una vista diferente del estado del encabezado de lista despu\u00e9s de una modificaci\u00f3n. En el caso de dm-thin, este autor tuvo un bloqueo del cuadro de producci\u00f3n debido a una falla de GP en la ruta process_deferred_bios. Esta funci\u00f3n vio un encabezado de lista v\u00e1lido en get_first_thin() pero cuando posteriormente desreferenciaba eso y lo convert\u00eda en un thin_c, obtuvo el interior del grupo de estructuras, ya que la lista ahora estaba vac\u00eda y se refer\u00eda a s\u00ed misma. El n\u00facleo en el que esto ocurri\u00f3 imprimi\u00f3 una advertencia sobre la saturaci\u00f3n de un refcount_t y un error UBSAN por un acceso a cpuid fuera de los l\u00edmites en el spinlock en cola, antes del fallo en s\u00ed. Cuando se examin\u00f3 el kdump resultante, fue posible ver otro hilo esperando pacientemente en elsynchronous_rcu de thin_dtr. La llamada thin_dtr logr\u00f3 sacar el thin_c de la lista de thins activa (y hacer que sea la \u00faltima entrada en la lista de active_thins) justo en el momento equivocado, lo que provoc\u00f3 este bloqueo. Afortunadamente, la soluci\u00f3n aqu\u00ed es sencilla. Cambie la funci\u00f3n get_first_thin() para usar list_first_or_null_rcu() que realiza solo un \u00fanico READ_ONCE() y devuelve NULL si la lista ya est\u00e1 vac\u00eda. Esto se ejecut\u00f3 contra las suites de aprovisionamiento fino del conjunto de pruebas devicemapper para eliminar y suspender y no se observaron regresiones."}], "lastModified": "2025-11-03T21:19:03.373", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "06E3D8A0-2ABD-417B-B56D-AA20015A3FEF", "versionEndExcluding": "5.4.290", "versionStartIncluding": "3.15.1"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "F732162B-ED7E-4367-A5C2-B24FD9B0D33B", "versionEndExcluding": "5.10.234", "versionStartIncluding": "5.5"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "71A3AFDC-A3CA-454F-8917-E998BBDE36F8", "versionEndExcluding": "5.15.177", "versionStartIncluding": "5.11"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "9AFD566B-ECC6-46F1-92F7-12A615D5685F", "versionEndExcluding": "6.1.125", "versionStartIncluding": "5.16"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "33E12097-C88A-45B4-9677-2A961A08DD3E", "versionEndExcluding": "6.6.72", "versionStartIncluding": "6.2"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "02D604F6-10D1-4F7B-A022-0888406A1121", "versionEndExcluding": "6.12.10", "versionStartIncluding": "6.7"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:3.15:-:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "F138B0D1-8A71-47E3-B203-17061370DFD9"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:3.15:rc4:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "65A165BE-BAC4-4DC6-A333-72A486481AD0"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:3.15:rc5:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "3E897136-35E2-48BC-BF4F-2160B2A00D69"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:3.15:rc6:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "6598CE29-AAD6-4FD9-B662-6AEE6812A8E7"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:3.15:rc7:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "C02C163F-D1BD-4284-B652-AFB5EAFE9879"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:3.15:rc8:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "D28A725C-B7B8-4634-8C5C-FC56439B51AF"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:6.13:rc1:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "62567B3C-6CEE-46D0-BC2E-B3717FBF7D13"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:6.13:rc2:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "5A073481-106D-4B15-B4C7-FB0213B8E1D4"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:6.13:rc3:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "DE491969-75AE-4A6B-9A58-8FC5AF98798F"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:6.13:rc4:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "93C0660D-7FB8-4FBA-892A-B064BA71E49E"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:6.13:rc5:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "034C36A6-C481-41F3-AE9A-D116E5BE6895"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:6.13:rc6:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "8AF9DC49-2085-4FFB-A7E3-73DFAFECC7F2"}], "operator": "OR"}]}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}