{"resultsPerPage":1,"startIndex":0,"totalResults":1,"format":"NVD_CVE","version":"2.0","timestamp":"2026-04-21T04:46:00.375","vulnerabilities":[{"cve":{"id":"CVE-2025-21664","sourceIdentifier":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","published":"2025-01-21T13:15:10.053","lastModified":"2025-11-03T21:19:03.373","vulnStatus":"Modified","cveTags":[],"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 función list first de rcu-safe La documentación en rculist.h explica la ausencia de list_empty_rcu() y advierte a los programadores que no confíen en una secuencia list_empty() -> list_first() en el código 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 situación en la que list_empty() ve una entrada de lista válida, pero el list_first() posterior ve una vista diferente del estado del encabezado de lista después de una modificación. En el caso de dm-thin, este autor tuvo un bloqueo del cuadro de producción debido a una falla de GP en la ruta process_deferred_bios. Esta función vio un encabezado de lista válido en get_first_thin() pero cuando posteriormente desreferenciaba eso y lo convertía en un thin_c, obtuvo el interior del grupo de estructuras, ya que la lista ahora estaba vacía y se refería a sí misma. El núcleo en el que esto ocurrió imprimió una advertencia sobre la saturación de un refcount_t y un error UBSAN por un acceso a cpuid fuera de los límites en el spinlock en cola, antes del fallo en sí. Cuando se examinó el kdump resultante, fue posible ver otro hilo esperando pacientemente en elsynchronous_rcu de thin_dtr. La llamada thin_dtr logró sacar el thin_c de la lista de thins activa (y hacer que sea la última entrada en la lista de active_thins) justo en el momento equivocado, lo que provocó este bloqueo. Afortunadamente, la solución aquí es sencilla. Cambie la función get_first_thin() para usar list_first_or_null_rcu() que realiza solo un único READ_ONCE() y devuelve NULL si la lista ya está vacía. Esto se ejecutó contra las suites de aprovisionamiento fino del conjunto de pruebas devicemapper para eliminar y suspender y no se observaron regresiones."}],"metrics":{"cvssMetricV31":[{"source":"nvd@nist.gov","type":"Primary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","baseScore":5.5,"baseSeverity":"MEDIUM","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"NONE","availabilityImpact":"HIGH"},"exploitabilityScore":1.8,"impactScore":3.6}]},"weaknesses":[{"source":"nvd@nist.gov","type":"Primary","description":[{"lang":"en","value":"NVD-CWE-noinfo"}]}],"configurations":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.15.1","versionEndExcluding":"5.4.290","matchCriteriaId":"06E3D8A0-2ABD-417B-B56D-AA20015A3FEF"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.5","versionEndExcluding":"5.10.234","matchCriteriaId":"F732162B-ED7E-4367-A5C2-B24FD9B0D33B"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.11","versionEndExcluding":"5.15.177","matchCriteriaId":"71A3AFDC-A3CA-454F-8917-E998BBDE36F8"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.16","versionEndExcluding":"6.1.125","matchCriteriaId":"9AFD566B-ECC6-46F1-92F7-12A615D5685F"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.2","versionEndExcluding":"6.6.72","matchCriteriaId":"33E12097-C88A-45B4-9677-2A961A08DD3E"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.7","versionEndExcluding":"6.12.10","matchCriteriaId":"02D604F6-10D1-4F7B-A022-0888406A1121"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:3.15:-:*:*:*:*:*:*","matchCriteriaId":"F138B0D1-8A71-47E3-B203-17061370DFD9"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:3.15:rc4:*:*:*:*:*:*","matchCriteriaId":"65A165BE-BAC4-4DC6-A333-72A486481AD0"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:3.15:rc5:*:*:*:*:*:*","matchCriteriaId":"3E897136-35E2-48BC-BF4F-2160B2A00D69"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:3.15:rc6:*:*:*:*:*:*","matchCriteriaId":"6598CE29-AAD6-4FD9-B662-6AEE6812A8E7"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:3.15:rc7:*:*:*:*:*:*","matchCriteriaId":"C02C163F-D1BD-4284-B652-AFB5EAFE9879"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:3.15:rc8:*:*:*:*:*:*","matchCriteriaId":"D28A725C-B7B8-4634-8C5C-FC56439B51AF"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:6.13:rc1:*:*:*:*:*:*","matchCriteriaId":"62567B3C-6CEE-46D0-BC2E-B3717FBF7D13"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:6.13:rc2:*:*:*:*:*:*","matchCriteriaId":"5A073481-106D-4B15-B4C7-FB0213B8E1D4"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:6.13:rc3:*:*:*:*:*:*","matchCriteriaId":"DE491969-75AE-4A6B-9A58-8FC5AF98798F"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:6.13:rc4:*:*:*:*:*:*","matchCriteriaId":"93C0660D-7FB8-4FBA-892A-B064BA71E49E"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:6.13:rc5:*:*:*:*:*:*","matchCriteriaId":"034C36A6-C481-41F3-AE9A-D116E5BE6895"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:6.13:rc6:*:*:*:*:*:*","matchCriteriaId":"8AF9DC49-2085-4FFB-A7E3-73DFAFECC7F2"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/12771050b6d059eea096993bf2001da9da9fddff","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"]},{"url":"https://git.kernel.org/stable/c/6b305e98de0d225ccebfb225730a9f560d28ecb0","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"]},{"url":"https://git.kernel.org/stable/c/802666a40c71a23542c43a3f87e3a2d0f4e8fe45","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"]},{"url":"https://git.kernel.org/stable/c/80f130bfad1dab93b95683fc39b87235682b8f72","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"]},{"url":"https://git.kernel.org/stable/c/cbd0d5ecfa390ac29c5380200147d09c381b2ac6","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"]},{"url":"https://git.kernel.org/stable/c/cd30a3960433ec2db94b3689752fa3c5df44d649","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"]},{"url":"https://git.kernel.org/stable/c/ec037fe8c0d0f6140e3d8a49c7b29cb5582160b8","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":["Patch"]},{"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"}]}}]}